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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

B

Science and Applications Traceability Matrix

The Science and Applications Traceability Matrix (SATM; Table B.1) provided the basis for much of the committee’s deliberations and forms the foundation of its recommendations. The process for developing this matrix, including the central role of the panels, is summarized in Chapter 3.

The SATM is organized by panel and color coded, with blue-shaded columns identifying science and applications questions and objectives and green-shaded columns identifying associated observation and measurement needs to address those questions and objectives. Note that Table 3.3 is identical to the blue portion of the SATM. The content of the green columns represents panel guidance to the steering committee. The steering committee did more extensive implementation analysis (including cost analysis through the Cost Assessment and Technical Evaluation (CATE) process, where appropriate) to determine its observing system priorities (Table 3.3). As such, the green columns should not be taken as recommendations or even definitive guidance, but rather as noncomprehensive suggestions.

Columns in the SATM consist of the following:

Societal or Science Question. The top-level science or applications question driving the research need.
Earth Science/Application Objective. A specific objective needed to address the related science or societal question.
Science/Applications Importance. The relative priority of pursuing a given objective, ranked as Most Important, Very Important, or Important (described further in Chapter 3).
Geophysical Observable. The geophysical parameter to be observed in order to pursue the related objective.
Measurement Parameters. The measurement specifications associated with the observable.
Example Measurement Approaches. Examples of measurement methods that can be used to measure the observable to achieve the requirements of the measurement parameters. Entries in these columns reflect the judgment of the panels, but are not definitive. A thorough trade analysis was not performed to identify the best measurement approach for each observation, no instrument or

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

mission design was performed, and no costing was established. Note that examples in either the Program of Record (POR) or Targeted Observable (TO) subcolumns are not complete and may even be absent for a number of reasons, due to the complexity of the SATM process. Blank cells should not be considered as evidence that no relevant POR is available or new measurement (TO) is needed.
- Method. Candidate measurement methods.
- POR. Examples of POR instruments or missions that have made or will make similar measurements. The POR numbers refer to the Committee on Earth Observing Satellites (CEOS) Catalog categories, as summarized in Table B.2. Listed names are instruments or missions that have been specifically identified.
- TO. Entries in the ESAS 2017 Targeted Observables table (Appendix C) that may, depending on implementation approach, contribute to the needed measurement(s).

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

Table B.1 begins on next set of facing pages.

TABLE B.2 Committee on Earth Observing Satellites Catalog Categories

Program of Record Number	Instrument Technology
1	Absorption-band microwave (MW) radiometer/spectrometer
2	Atmospheric lidar
3	Broadband radiometer
4	Cloud and precipitation radar
5	Doppler lidar
6	Global Navigation Satellite Systems (GNSS) radio-occultation receiver
7	GNSS receiver
8	Gradiometer/accelerometer
9	High-resolution optical imager
10	High-resolution nadir-scanning infrared (IR) spectrometer
11	High-resolution nadir-scanning shortwave (SW) spectrometer
12	Imaging radar (Synthetic Aperture Radar)
13	Laser Retroreflector
14	Laser altimeter
15	Lightning imager
16	Limb-scanning IR spectrometer
17	Limb-scanning MW spectrometer
18	Limb-scanning SW spectrometer
19	Magnetometer
20	Medium-resolution IR spectrometer
21	Medium-resolution IR spectro-radiometer
22	Multichannel/direction/polarization radiometer
23	Multipurpose imaging MW radiometer
24	Multipurpose imaging visible (VIS)/IR radiometer
25	Narrow-band channel IR radiometer
26	Nonscanning MW radiometer
27	Radar altimeter
28	Radar scatterometer
29	Radio-positioning system
30	Satellite-to-satellite ranging system
31	Solar irradiance monitor

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

TABLE B.1 ESAS 2017 Consolidated Science and Applications Traceability Matrix

KEY:	Square brackets: Nonspace observations or related commitments Curly brackets: Space observations with non-NASAS/NOAA/USGS assets, such as non-U.S. or databuys

GLOBAL HYDROLOGICAL CYCLES AND WATER RESOURCES PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
QUESTION H-1. Coupling the Water and Energy Cycle. How is the water cycle changing? Are changes in evapotranspiration and precipitation accelerating, with greater rates of evapotranspiration and thereby precipitation, and how are these changes expressed in the space-time distribution of rainfall, snowfall, evapotranspiration, and the frequency and magnitude of extremes such as droughts and floods?	H-1a. Develop and evaluate an integrated Earth system analysis with sufficient observational input to accurately quantify the components of the water and energy cycles and their interactions, and to close the water balance from headwater catchments to continental-scale river basins.	Most Important	Energy and water fluxes in the boundary or surface layer: solar (direct and reflected) and longwave radiation (downwelling and emitted), sensible and latent heat exchange, and soil heat flux.	Surface solar and longwave radiation balances, which are needed to estimate the other energy balance parameters, to within 10 W/m² accuracy at 1 km resolution globally, four times daily.	Downscale CERES-like observations to finer spatial resolutions (1 km) and eliminate systematic errors. See H-1b and H-1c.	POR-1, 3, 10, 20, 21, 23, 24, 25	TO-17, 18
		Most Important			Model and data integration with capabilities to estimate moist processes in atmosphere, land and terrestrial biosphere.	POR-1, 6, 9	TO-13
	H-1b. Quantify rates of precipitation and its phase (rain and snow/ice) worldwide at convective and orographic scales suitable to capture flash floods and beyond.	Most Important	Precipitation rate and phase (rain or snow).	Diurnal cycle of precipitation at 1 (desirable) or 4 km (needed) scales (rain and snow) with accuracy of 0.2 mm/hr for rainfall and 1 mm/hr for snow, at finer scales in selected areas such as mountainous regions.	Multi-frequency radar and radiometer system similar to GPM/CloudSat as well as aerosol capabilities for continued improvement in precipitation process understanding, precipitation rate observations, and long term monitoring for change detection.	POR-4, 23, 25	TO-5, 13
	H-1c. Quantify rates of snow accumulation, snowmelt, ice melt, and sublimation from snow and ice worldwide at scales driven by topographic variability.	Most Important	Snow water equivalent (SWE).	Global SWE at 1 (desirable) or 4 km (needed) resolution every 3-5 days, to 10% accuracy for SWE values to 1 m.	Existing passive microwave for global scale okay for SWE values to ~200 mm. Problematic for deep snow in heterogeneous terrain.	POR-23	TO-16, 19
			Snow water equivalent (SWE).	In mountains, SWE at ~100 m resolution suitable for SWE values to 2.5 m.	In mountains, measure depth (Ka-band radar or laser altimeter) and density (SAR).	POR-17 (KaRIn, SWOT)	TO-16, 19
			Snow and glacier albedo and temperature.	Spectral albedo of subpixel snow and glaciers at weekly intervals to an accuracy to estimate absorption of solar radiation to 10%. Ice/snow surface temperature to ±1 K. At spatial resolution of 30 to 100 m.	Imaging spectrometer to understand seasonal variability. Develop methods and calibration for multispectral sensors for weekly worldwide coverage. Panchromatic multiangle radiometer. Thermal emission radiometer for temperature.	POR-22	TO-18
QUESTION H-2. Prediction of Changes. How do anthropogenic changes in climate, land use, water use, and water storage, interact and modify the water and energy cycles locally, regionally, and globally and what are the short- and long-term consequences?	H-2a. Quantify how changes in land use, water use, and water storage affect evapotranspiration rates, and how these in turn affect local and regional precipitation systems, groundwater recharge, temperature extremes, and carbon cycling.	Very Important	Latent heat flux at 3 (desirable) to 6 hour (useful) resolution during daytime intervals and at 1 km spatial scale with better than 10 W/m² accuracy.	Temperature of soil and vegetation separately, 40-100 m spatial resolution, accuracy of ±1 K, at a temporal frequency to resolve the diurnal cycle.	Emitted infrared radiation in 4 µm and 11 µm wavelength regions, possibly free flyers to get desired frequency of four times daily.	POR-3, 9, 10, 20, 24, 25	TO-13, 18
				Boundary layer vapor pressure deficit profile and near-surface humitidy, 1-10 km resolution, at least four times during daytime with better than 1 hPa accuracy. Boundary-layer wind speed over land, including heterogeneous terrain, is needed to estimate surface fluxes.	AIRS for atmospheric moisture. Add capability for near surface profile (profile within the first 100 m).	POR-1, 6, 20, 23	TO-4, 13
				Soil moisture profile to 4% volumetric accuracy in top 1 m of the soil column.	Passive microwave dual-channel L- and P-band radiometer, with polarization for four Stokes parameters, at spatial resolution 20-60 km. Active microwave dual-channel L- and P-band radar, VV, HH, and HV polarization at spatial resolution of 100 m to 1 km.	POR-23	TO-17

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

GLOBAL HYDROLOGICAL CYCLES AND WATER RESOURCES PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
				Albedo of vegetation and soil separately, to an accuracy to estimate absorption of solar radiation to 10 W/m², at weekly intervals at field scale 30-60 m spatial resolution.	Imaging spectrometer to develop methods and to calibrate multispectral sensors for worldwide coverage.	POR-22, 24	TO-18
	H-2b. Quantify the magnitude of anthropogenic processes that cause changes in radiative forcing, temperature, snowmelt, and ice melt, as they alter downstream water quantity and quality.	Important	Snow and ice albedo, contaminant type (dust, soot) and concentration, land cover. Surface temperature. Glacier, river, and lake mapping and characterization.	Spectral snow and ice albedo, optical properties and concentrations of contaminants (dust and soot), surface temperature to ±1 K.	Imaging spectrometry at resolution to capture topographic variability, typically ~30 m. Lidar to measure vegetation properties. Thermal emission radiometer for temperature, prefer to 30 m spatial resolution. 5-10 m spatial multiband imaging for worldwide coverage of land, rivers, lakes, and glaciers.	POR-3, 9, 12, 14, 22	TO-18, 20
	H-2c. Quantify how changes in land use, land cover, and water use related to agricultural activities, food production, and forest management affect water quality and especially groundwater recharge, threatening sustainability of future water supplies.	Most Important	Recharge rates (i.e., space-time rates of change in groundwater storage and availability) at 1 km (desired) up to 10 km (useful) scale globally at 10-day intervals with accuracy of better than ±1 mm/day	Soil moisture profile to 4% volumetric accuracy in top 1 m of the soil column.	See H-2a for Measurement Approach to soil moisture.	POR-23	TO-17
				Changes in vadose zone moisture and in groundwater storage. Changes in groundwater levels. Changes in snow water equivalent.	Gravimetric methods.	POR-30	TO-9, 17
				Land-surface deflection to 1 cm accuracy, 100 m spatial resolution.	L-band InSAR. Perhaps combined with airborne lidar.	POR-12	TO-19
			Differences between precipitation and evapotranspiration to an accuracy whereby estimates of their difference have smaller errors than the magnitude of groundwater recharge.	See H-2a for Measurement Parameters for evapotranspiration.	See H-2a for Measurement Approaches for evapotranspiration.	-	TO-17
				Rainfall at fine space (1 km) and time (15 min) resolution in selected areas to properly capture accumulation at field scales and partition between canopy intercept, infiltration and runoff.	High-resolution geostationary radar. Observationally constrained mesoscale models; typical constraints are active microwave backscattering coefficients, passive microwave brightness temperatures, and geostationary VIS/IR measurements.	-	TO-5, 9, 17
QUESTION H-3. Availability of Freshwater and Coupling with Biological Cycles. How do changes in the water cycle impact local and regional freshwater availability, alter the biotic life of streams, and affect ecosystems and the services these provide?	H-3a. Develop methods and systems for monitoring water quality for human health and ecosystem services.	Important	Turbidity, total suspended sols and suspended sols particle size distribution in estuaries and coastal regions, salinity to 10 psu, temperature to 1 K, and chlorophyll.	At spatial scales small enough to resolve streams, ~10 m. Appropriate scale and resolution for onsite management for water quality.	Imaging spectrometer for worldwide land coverage and to develop methods and calibrate multispectral sensors for more frequent coverage.	-	TO-3, 18
	H-3b. Monitor and understand the coupled natural and anthropogenic processes that change water quality, fluxes, and storages in and between all reservoirs (atmosphere, rivers, lakes, groundwater, and glaciers), and the response to extreme events.	Important	Land cover and vegetation condition, soil moisture, land use, burned area after fire, and terrain slope.	At scales small enough to resolve local areas contributing to water quality and landslides: at spatial resolution of 100 m (desirable) to 1 km (useful).	Models that link precipitation, land use, land cover, and topography to water quality.	POR-9, 10, 12, 21	TO-3, 18, 20
	H-3c. Determine structure, productivity, and health of plants to constrain estimates of evapotranspiration.	Important	Vegetation biophysical condition (color and water content), vapor pressure deficit between vegetation and atmosphere, soil moisture profile, leaf area index and vegetation fraction, broadband and spectral albedo of vegetation.	Water use efficiency of plants as they respond to moisture stress.	Models that link vegetation’s radiative signal with processes of evapotranspiration.	POR-10	Modeling
			Structure of vegetation canopy.	Amount of woody biomass and leaf area index. 1 to 4 points sample points per square meter with 2 to 4 returns per point for moderately to heavily forested regions	Lidar, P-band radar.	POR-12, 14	TO-20

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

GLOBAL HYDROLOGICAL CYCLES AND WATER RESOURCES PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
				and areas with intensive agriculture. Vegetation fraction at 30-100 m resolution and vertical profile of vegetation (canopy-understory-bare soil)
			Photosynthetic rate.	Solar induced fluorescence.	Imaging spectrometry within the Fraunhofer bands, but at 100 m scale.	POR-32	-
*QUESTION H-4.* How does the water cycle interact with other Earth system processes to change the predictability and impacts of hazardous events and hazard-chains (e.g., floods, wildfires, landslides, coastal loss, subsidence, droughts, human health, and ecosystem health), and how do we improve preparedness and mitigation of water-related extreme events?	H-4a. Monitor and understand hazard response in rugged terrain and land margins to heavy rainfall, temperature and evaporation extremes, and strong winds at multiple temporal and spatial scales. This socioeconomic priority depends on success of addressing H-1b and H-1c, H-2a, and H-2c.	Very Important	Magnitude and frequency of severe storms. Depth and extent of floods.	Precipitation, snowmelt, water depth, and water flow in soil at time and space scales consistent with events.	For precipitation and snow: Similar to SWOT but at finer spatial resolution.	See H-1b and H-1c	See H-1b and H-1c
		Very Important			For River Discharge: Similar to SWOT but at finer spatial resolution.	POR-26 (SWOT)
	H-4b. Quantify key meteorological, glaciological, and solid Earth dynamical and state variables and processes controlling flash floods, and rapid hazard chains to improve detection, prediction, and preparedness. (This is a critical socioeconomic priority that depends on success of addressing H-1b, H-1c, and H-4a).	Important	Rainfall intensity and volume for storms in the 95th percentile of values specific to areas, especially estimates in mountainous terrain where other measurement sources are not available, soil moisture, SWE, and glacier changes.	Precipitation, snowmelt, and flow in soil and glaciers at time and space scales consistent with events.	See measurement approaches associated with Objective H-2c.	POR-23	TO-17
	H-4c. Improve drought monitoring to forecast short-term impacts more accurately and to assess potential mitigations. This is a critical socioeconomic priority that depends on success of addressing H-1b, H-1c, and H-2c.	Important	Soil moisture, vegetation moisture, cumulative evapotranspiration, and SWE.	See specifications associated with Objective H-1a.	See measurement approaches associated with Objective H-1a.	POR-12, 23	TO-17
	H-4d. Understand linkages between anthropogenic modification of the land, including fire suppression, land use, and urbanization on frequency of, and response to, hazards. This is tightly linked to H-2a, H-2b, H-4a, H-4b, and H-4c.	Important	Susceptibility of forest and brushlands to fire, land use change, urban characteristics.	Dry fuel load.	Imaging spectrometer for worldwide land coverage and to develop methods and calibrate multispectral sensors for more frequent coverage.		TO-18
				Land use and land cover, global scale monthly at 30-100 m resolution, selected areas annually at 5-10 m resolution, surface soil moisture, surface temperature, evapotranspiration at scale of topographic variability, typically ~30 m.	For LULCC: Multispectral sensors at varying resolution to merge spatial and time scales.	POR-9, 11, 12
					For Soil Moisture: Multispectral sensors at varying resolution to merge spatial and time scales.		TO-20
				Urban form and textures at scales to resolve distinctive features, typically 5-10 m, annually.	Imaging spectrometer for worldwide land coverage and to develop methods and calibrate multispectral sensors for more frequent coverage.	POR-9, 11, 12	TO-18, 20

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

WEATHER AND AIR QUALITY PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
QUESTION W-1. Planetary Boundary Layer Dynamics. What planetary boundary layer (PBL) processes are integral to the air-surface (land, ocean and sea ice) exchanges of energy, momentum, and mass, and how do these impact weather forecasts and air quality simulations?	W-1a. Determine the effects of key boundary layer processes on weather, hydrological, and air quality forecasts at minutes to subseasonal time scales.	Most Important	3D temperature in PBL	Horizontal resolution 20 km, vertical resolution 0.2 km, temporal resolution 3 hr, 0.3 K/0.3 K	Polar/geo IR and microwave sounders, complemented by airborne and surface observations	POR-1, 6, 20, 24, 25	TO-13
			3D humidity in PBL	Horizontal resolution 20 km, vertical resolution 0.2 km, temporal resolution 3 hr, 0.3 g/kg	Polar/geo IR and microwave sounders, complemented by airborne and surface observations	POR-1, 6, 20, 24, 25	TO-13
			3D horizontal wind vector in PBL	Horizontal resolution 20 km, vertical resolution 0.2 km, temporal resolution 3 hr, 1 m/s	Doppler wind lidar, AMVs from multiangle VIS/IR (occasionally reaching PBL), scatterometer measurements of near-surface winds over ocean	POR-25	TO-4, 11
			3D PM component and trace gas (ozone, NO₂) concentrations	Horizontal resolution 5 km, vertical resolution 0.2 km, temporal resolution 2 hr	See approaches listed under W-6 below.	POR-2, 10, 11, 22	TO-1, 12
			2D PBL height	Horizontal resolution 20 km, temporal resolution 3 hr, 0.1 km	Lidar (e.g., CALIPSO)	POR-2, 6	TO-1, 13
			2D PBL cloud LWP	Horizontal resolution 20 km, 20%	Microwave radiometer	POR-1, 23	TO-5
			2D cloud base	Horizontal resolution 20 km, 0.1 km	Lidar	POR-2, 4	TO-5
			2D precipitation	Horizontal resolution 10 km, 20%	Passive microwave (e.g., GPM), radar; complemented by rain gauges and radar over land	POR-1, 4, 23	TO-5
QUESTION W-2. Larger Range Environmental Predictions. How can environmental predictions of weather and air quality be extended to seamlessly forecast Earth system conditions at lead times of 1 week to 2 months?	W-2a. Improve the observed and modeled representation of natural, low-frequency modes of weather/climate variability (e.g., MJO, ENSO), including upscale interactions between the large-scale circulation and organization of convection and slowly varying boundary processes to extend the lead time of useful prediction skills by 50% for forecast times of 1 week to 2 months. Advances require improved: (1) Process understanding and assimilation / modeling capabilities of atmospheric convection, mesoscale organization, and atmosphere and ocean boundary layers, (2) Global initial conditions relevant to these quantities/processes. Observations needed for boundary layer, surface conditions, and convection are described in W-1, W-3, and W-4, respectively.	Most Important	Vertical temperature profile	Boundary layer through middle atmosphere; threshold Horizontal resolution 5 km, objective Horizontal resolution 3 km, both at 1 km Vertical resolution; threshold refresh 3 hr, objective refresh global 90 min and CONUS 60 min; measured with 1 K rms	Polar/geo IR and microwave sounders PLUS GNSS-RO	POR-1, 6, 20, 25	TO-13
			Vertical water vapor profile	Boundary layer through middle atmosphere; threshold Horizontal resolution 5 km, objective Horizontal resolution 3 km, both at 1 km Vertical resolution; threshold refresh 3 hr, objective refresh global 90 min and CONUS 60 min; measured with 10% LTH rms and 20% UTH rms	Polar/geo IR and microwave sounders PLUS GNSS-RO	POR-1, 6, 20, 25	TO-13
			Vertical profiles of horizontal vector winds	Boundary layer through middle atmosphere; threshold Horizontal resolution 5 km, objective Horizontal resolution 3 km, both at 1 km Vertical resolution; threshold refresh 3 hr, objective refresh global 90 min and CONUS 60 min; measured at 3 m/s rms	Doppler wind lidar	POR-5	TO-4
			Vertical profiles of horizontal vector winds		AMVs from IR, WV, and visible imagers and hyperspectral sounders	POR-1, POR-20	TO-13
			Vertical profile of atmospheric O₃, aerosols, and dust for subseasonal	From surface through middle atmosphere mid-troposphere for aerosols and dust; through stratosphere for ozone.	Lidar, stereo visible, UV backscatter, MW limb sounding	POR-11, 17, 18	TO-12
			Vertical distributions of clouds and precipitation particles	From surface through lower stratosphere; Vertical resolution 1 km/10 km; ice water path to within 25%, LWP to within 25%	MW for LWP, submillimeter with radar for IWP; GNSS-RO (L-band) dual-pol - LHCP is new	POR-2, 4	TO-5

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

WEATHER AND AIR QUALITY PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			Precipitation: total amount and rate	Horizontal resolution 10 km, 20%	Passive microwave (e.g., GPM), radar; complemented by rain gauges and radar over land	POR-4, 23	TO-5
			Surface pressure	To within 1 mb			TO-5
			Vertical profiles of latent heating		GPROF from TRMM, also from CloudSat, GPM	POR-23	TO-5
			Sea-ice coverage	5 km resolution; 80% coverage daily; uncertainty 10%; 10 km horizontal	Doppler scatterometer or scatterometer, SAR, high-resolution imager, [ice stations]	POR-11, 12, 21, 23, 28	TO-11
			Sea-surface temperature	0.2 K random uncertainty in 25 × 25 km area; 80% daily coverage; 3 to 5 km resolution.	IR radiometer, microwave radiometer, [complemented by in situ buoys and gliders]	POR-11, 21, 23, 24
			Land-surface temperature	0.6 K random uncertainty in 25 × 25 km area, 80% daily coverage, 3-5 km resolution, with 1 km resolution desired.	IR radiometer (e.g., MODIS, VIIRS, AIRS, CrIS), complemented by modeling	POR-11, 21, 23	TO-18
			Snow coverage (for exposed land and ice)	An average of 1‐2 samples (overpasses) per day per 100 to 200 km region; 1 to 10 km resolution; random errors of two times the resolution.	Visible imager (coverage), passive microwave, radar, and lidar (for snow depth/water equivalent)	POR-11, 21, 23	TO-16
			Soil moisture (surface to root zone)	Random errors of 10% in fraction of saturation, while 1 km resolution is desired, 25 km is useful.	Multichannel radiometer, scatterometer (e.g., SMOS, SMAP). NOTES: C-band scatterometry has worked well in Europe, whereas in the US radiometry is more common. Both seem to work.	POR-12, 23, 27	TO-17
			Ocean mixed layer depth (heat content), sea-surface height, and bottom pressure	Global refresh 10 days; Horizontal 25 km; 0.5 W/m²/yr per decade.	Altimeter (e.g., Jason, SARAL), gravimeter (e.g., GRACE), [in situ profiles]	POR-27	TO-10
			Sea-ice thickness	50 cm; 10 km; 24 hr.	Altimeter (e.g., Jason, ICESat-2)	POR-14	TO-7
			Snow water equivalent	Horizon resolution of 20 km, once per day, 10%, Desire 4 km resolution, on a 3 to 5 day scale.	Passive microwave, radar, and SAR	POR-17, 23	TO-16, 19
QUESTION W-3. Surface Spatial Variations Impacts on Mass and Energy Transfers. How do spatial variations in surface characteristics (influencing ocean and atmospheric dynamics, thermal inertia, and water) modify transfer between domains (air, ocean, land, cryosphere) and thereby influence weather and air quality?	W-3a. Determine how spatial variability in surface characteristics modifies regional cycles of energy, water and momentum (stress) to an accuracy of 10 W/m² in the enthalpy flux, and 0.1 N/m² in stress, and observe total precipitation to an average accuracy of 15% over oceans and/or 25% over land and ice surfaces averaged over a 100 × 100 km region and 2-to 3-day time period.	Very Important	Ocean surface vector wind or surface wind stress	An average of 1‐2 samples (overpasses) per day per 100 to 200 km region; 5 to 10 km resolution; 0.02 N/m² for 100 km scales and 1 to 2 day averages (this is analogous to vector component wind random errors <1 m/s for the proposed sampling).	Scatterometer OR polarimetric radiometer. NOTES: SAR could provide wind vectors but directional accuracy not sufficient to calculate curl.	POR-28	TO-11
			Ocean surface vector current	An average of 1‐2 samples (overpasses) per day per 100 to 200 km region for a high inclination orbit; 5 to 10 km resolution; Random errors ≤0.02 m/s for 100 km scales and 1 to 2 day averages (this is analogous to current random errors <0.5 m/s for the proposed sampling); Coincidence with wind observations.	Doppler scatterometer, HF radar (near coastal only, roughly 100 km from shore). NOTES: Wide swath altimetry will be complementary but is not an alternative. SAR could provide one vector component, but the accuracy and sampling are questionable. Accurate surface currents (true surface, not subsurface) are new and unique.		TO-11
			Subsurface current	Already exceeded by the global drifting buoy network: 1,250 drifting buoys with global ocean coverage and hourly locations.	[Surface drifting buoys drogued to 15 m depth, gliders]	TERRESTRIAL	TERRESTRIAL

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

WEATHER AND AIR QUALITY PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			Sea-ice motion	3 km per day; 25 km horizontal, 24 hr.	Doppler scatterometer or scatterometer, SAR, high-resolution imager, (ice stations). NOTES: Synergetic with observation of sea-ice age and extent, soil moisture, vegetation, snow, ocean mixed layer and surface currents.	POR-11, 12, 21	TO-11
			Sea-ice coverage	5 km resolution; 80% coverage daily; uncertainty 10%; 10 km horizontal	Doppler scatterometer or scatterometer, SAR, high-resolution imager, [ice stations]	POR-11, 12, 21, 23, 28	TO-11
			Sea-surface temperature	0.2 K random uncertainty in 25 × 25 km area; 80% daily coverage; 3 to 5 km resolution.	IR radiometer, microwave radiometer, [complemented by in situ buoys and gliders]	POR-11, 21, 23, 24
			Sea-ice surface temperature	0.6 K random uncertainty in 25 × 25 km area; 80% daily coverage; 3-5 km resolution.	IR radiometer (e.g., MODIS, VIIRS, AIRS, CrIS), complemented by modeling	POR-11, 21, 23	TO-18
			Land-surface temperature	0.6 K random uncertainty in 25 × 25 km area, 80% daily coverage, 3-5 km resolution, with 1 km resolution desired.	IR radiometer (e.g., MODIS, VIIRS, AIRS, CrIS), complemented by modeling	POR-11, 21, 23	TO-18
			Snow coverage (for exposed land and ice)	An average of 1‐2 samples (overpasses) per day per 100 to 200 km region; 1 to 10 km resolution; random errors of boundaries of two times the resolution.	Visible imager (coverage), passive microwave, radar, and lidar (for snow depth/water equivalent)	POR-11, 21, 23	TO-16
			Soil moisture (surface to root zone)	Random errors of 10% in fraction of saturation while 1 km is desired, 25 km is useful.	Multichannel radiometer, scatterometer (e.g., SMOS, SMAP). NOTES: C-band scatterometry has worked well in Europe, whereas in the US radiometry is more common. Both seem to work.	POR-12, 23, 28	TO-15, 17
			Upper canopy moisture content	Random errors of 10% in fraction of saturation.	Multichannel radiometer, high frequency and high inclination angle scatterometer		TO-15, 17
			Significant wave height	5cm random error for a 25 km × 25 km area in one overpass.	Altimeter (for swell, wind wave compoent is well-estimated from surface winds), complemented by wave buoys	POR-26, 27	TO-21
			Columnar water vapor (all sky)	An average of 1‐2 samples (overpasses) per day per 50 km region; 5 to 10 km resolution; clear sky RMS errors within 3 mm; NWP needs higher revisit (1-6 hr).	Polar/geo IR and microwave sounders PLUS GNSS-RO	POR-21, 23, 24
			Cloud fraction	An average of 1‐2 samples (overpasses) per day per 50 km region, 5 to 10 km resolution, random errors <1 K in brightness temperature	Polar/geo IR	POR-11, 21, 24
			Ocean mixed layer depth (heat content), sea-surface height, and bottom pressure	Global refresh 10 days; Horizontal 7 km; 0.5 W/m²/yr per decade.	Altimeter (e.g., JASON, SARAL), gravimeter (e.g., GRACE), [in situ profiles]	POR-27	TO-10
			Boundary-layer height (via air temperature profile)	An average of 1‐2 samples (overpasses) per day per 50 km region; 5 to 10 km resolution; random errors 10 m in boundary‐layer height.	Lidar (e.g., CALIPSO)	POR-2, 6	TO-1
			Land surface emissivity	Horizon resolution of 20 km; once per day; 20%. Desire 0.1 km, resolve diurnal cycle 10%	Multiangle multichannel radiometer	POR-11, 21, 24	TO-13

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

WEATHER AND AIR QUALITY PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			Ice surface emissivity	Horizon resolution of 20 km; once per day; 0.02.	Multichannel radiometer	POR-11, 21, 23	TO-13
			Sea-surface height	10 cm random variability; six hourly; 10 km resolution.	Wide-swath altimeter, supported by microwave water vapor radiometer	POR-26, 27	TO-21
			Sea-surface salinity	An average of 1‐2 samples (overpasses) per 10 days per 100 to 200 km region; 50 km resolution; random erros of 0.2 psu in monthly average on a 100 × 100 km scale.	L-band radiometer, with co-aligned L-band scatterometer for roughness correction (e.g., SMAP, Aquarius, SMOS)	POR-12, 23	TO-15
			Sea-ice thickness	50 cm; 10 km; 24 hr.	Altimeter (e.g., JSON, ICESat-2)	POR-14	TO-7
			Snow water equivalent	Horizon resolution of 20 km; once per day; 20%. Desire 4 km resolution, on a 3-5 day scale.	Passive microwave, radar, and SAR	POR-17, 23	TO-16, 19
			Snow albedo and emissivity	Horizon resolution of 20 km; once per day; 0.01; 5 km resolution is desired.	Multichannel radiometer, microwave and IR/Vis	POR-11, 21, 22, 23, 24	TO-13
			2D surface precipitation	Ideally half hourly, but any additional sampling would be very valuable	Dual-frequencey radiometry, radar (e.g., GPM), [rain gauges and radar over land]	POR-4, 23	TO-5
			2D ocean surface color	An average of 1‐2 samples (overpasses) per day per 100 to 200 km region; 5 to 10 km resolution; random errors of 10 per meter.	Radiometry (e.g., PACE), optical imager (e.g., MODIS), OLCI, SLGI)	POR-1, 21, 23, 24	TO-3
			Vegetation characteristics	Land cover type, leaf-area index, vegatation fraction, canopy height	IR and visible radiometry, MODIS, VIIRS, imaging lidar (GEDI and ICESat2)	POR-9, 10, 12	TO-20
			Near surface air temperature and humidity	Horizon resolution of 20 km; temporal resolution of 3 hr; 0.3 K.	Microwave sounder (ocean), possibly hyperspectral IR for clear skies	POR-1, 6	TO-13
QUESTION W-4. Convective Storm Formulation Process. Why do convective storms, heavy precipitation, and clouds occur exactly when and where they do?	W-4a. Measure the vertical motion within deep convection to within 1 m/s and heavy precipitation rates to within 1 mm/hour to improve model representation of extreme precipitation and to determine convective transport and redistribution of mass, moisture, momentum, and chemical species.	Most Important	Vertical velocity	Global coverage; sample area 200 × 200 km; 5 year mission; Horizontal resolution 2 km; vertical resolution 200 m; temporal resolution 1 min over a 20-30 min period; accuracy 1 m/s.	Doppler radar		TO-5
			Precipitation rate	Global coverage; sample area 200 × 200 km; 5 year mission; Horizontal resolution 1 km; temporal resolution 1-5 min; accuracy 1 mm/hr.	Microwave, radar (e.g., GPM), [ground-based gauges and radar]		TO-5
			3D condensate	Accuracy 0.1 g/kg	Submillimeter multiple frequencies 180-900 GHz		TO-5
			Vertical profiles of horizontal	Accuracy 1 m/s	Doppler wind lidar	POR-5	TO-4
			winds		AMVs from IR/hyperspectral for wind estimation	POR-1, 20	TO-13
			3D water vapor	Vertical resolution 1 km; spatial resolution 500 m; temporal resolution 15 min; accuracy 0.5 g/kg.	IR, hyperspectral, [in situ: rawinsonde, aircraft]	POR-20	TO-13
QUESTION W-5. Air Pollution Processes and Distribution. What processes determine the spatio-temporal structure of important air pollutants and their concomitant adverse impact on human health, agriculture, and ecosystems?	W-5a. Improve the understanding of the processes that determine air pollution distributions and aid estimation of global air pollution impacts on human health and ecosystems by reducing uncertainty to <10% of vertically‐resolved tropospheric fields (including surface concentrations) of speciated particulate matter (PM), ozone (O₃), and nitrogen dioxide (NO2).	Most Important	PM concentration and properties, including speciation	PM: Aerosol Optical Depth to infer PM from 0‐2 km layer; Six observations during daylight hours to get diurnal distribution. 5 × 5 km² horizontal resolution. Spectral properties to infer PM speciation.	Combine advanced space-based observations, aircraft and ground-based observations with chemical transport modeling to infer surface levels. Geosynchronous orbit (GEO) to get temporal evolution and high horizontal resolution, in addition to LEO to get global coverage and allow for tracking long-range transport of pollution. A satellite at Lagrange point-1 may provide daylight-side coverage potentially hourly. PM: radiometric and polarimetric	POR-21 (MODIS), POR-22 (MISR, MAIA, 3MI), POR-24 (VIIRS), POR-11 (TEMPO)	TO-1, 2

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

WEATHER AND AIR QUALITY PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
					instrument (e.g., NASA EV MAIA, MISR)
			Ozone (O₃) concentration	O₃: Chappuis and other UV bands to infer O₃ from 0-2 km layer, and supported by modeling to infer surface level. Six observations during daylight hours to get diurnal distribution. Vertical resolution 500 m within BL. Horizontal resolution 5 × 5 km².	UV/visible spectrometer at geo (e.g., TEMPO); commercial aircraft vertical observations during takeoff/landing	POR-11 (OMI, TEMPO, TROPOMI), POR-21 (GEMS)
			NO₂ (nitrogen dioxide) concentration	NO₂: Lower tropospheric vertical distribution to infer NO₂ from 0-2 km layer. Six observations during daylight hours to get diurnal distribution. Vertical resolution 500 m within BL. Horizontal resolution 5 × 5 km².	UV/visible (e.g., Aura OMI, ESA TROPOMI, TEMPO); commercial aircraft vertical observations during takeoff/landing	POR-11 (OMI, TEMPO, TROPOMI), POR-21 (GEMS)
QUESTION W-6. Air Pollution Processes and Trends. What processes determine the long-term variations and trends in air pollution and their subsequent long-term recurring and cumulative impacts on human health, agriculture, and ecosystems?	W-6a. Characterize long-term trends and variations in global, vertically resolved speciated particulate matter (PM), ozone (O₃), and nitrogen dioxide (NO2) trends (within 20%/yr), which are necessary for the determination of controlling processes and estimation of health effects and impacts on agriculture and ecosystems.	Important	PM concentration and properties, including speciation	PM: Aerosol Optical Depth to infer PM from 0‐2 km layer; Six observations during daylight hours to get diurnal distribution. 5 × 5 km² horizontal resolution. Spectral properties to infer PM speciation.	Combine advanced space-based observations, aircraft and ground-based observations with chemical transport modeling to infer surface levels. Geosynchronous orbit (GEO) to get temporal evolution and high horizontal resolution, in addition to LEO to get global coverage and allow for tracking long-range transport of pollution. A satellite at Lagrange point 1 may provide daylight-side coverage potentially hourly. PM: radiometric and polarimetric instrument (e.g., NASA EV MAIA, MISR)	POR-21 (MODIS), POR-22 (MISR, MAIA, 3MI), POR-24 (VIIRS), POR-11 (TEMPO)	TO-1, 2
			O₃ (ozone) concentration	O₃: Chappuis and other UV bands to infer O₃ from 0-2 km layer, and supported by modeling to infer surface level. Six observations during daylight hours to get diurnal distribution. Vertical resolution 500 m within BL. Horizontal resolution 5 × 5 km².	UV/visible spectrometer at geo (e.g., TEMPO); commercial aircraft vertical observations during takeoff/landing	POR-11 (OMI, TEMPO, TROPOMI), POR-21 (GEMS)
			NO₂ (nitrogen dioxide) concentration	NO₂: Lower tropospheric vertical distribution to infer NO₂ from 0-2 km layer. Six observations during daylight hours to get diurnal distribution. Vertical resolution 500 m within BL. Horizontal resolution 5 × 5 km².	UV/visible (e.g., Aura OMI, ESA TROPOMI, TEMPO); commercial aircraft vertical observations during takeoff/landing	POR-11 (OMI, TEMPO, TROPOMI), POR-21 (GEMS)
QUESTION W-7. Tropospheric Ozone Processes and Trends. What processes determine observed tropospheric ozone (O₃) variations and trends and what are the concomitant impacts of these changes on atmospheric composition/chemistry and climate?	W-7a. Characterize tropospheric O₃ variations, including stratospheric-tropospheric exchange of O₃ and impacts on surface air quality and background levels.	Important	O₃ (ozone) concentration	O₃: Vertical distribution within the troposphere and lower stratosphere through a combination of ozonesondes (0.5 km vertical resolution, weekly sampling, to 70 hPa) and satellites (e.g., 0.5 km in vertical resolution in upper troposphere, lower stratosphere; 5.5 km² column observation with near surface (0-2 km) sensitivity).	Filter radiometer (e.g., Aura HIRDLS) for upper troposphere/lower stratosphere O₃ in conjunction with an ozonesonde network and commercial aircraft observations during takeoff/landing.	POR-11 (HIRDLS, TEMPO), POR-15 (LIS, GLM), POR-21 (GEMS)

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

WEATHER AND AIR QUALITY PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
QUESTION W-8. Methane Source Trends and Processes. What processes determine observed atmospheric methane (CH4) variations and trends and what are the subsequent impacts of these changes on atmospheric composition/chemistry and climate?	W-8a. Reduce uncertainty in tropospheric CH₄ concentrations and in CH₄ emissions, including uncertainties in the factors that affect natural fluxes.	Important	CH₄ (methane) concentration	CH₄ column (LEO): 7 × 7 km² horizontal resolution; daily overpass; precision = 0.6% (upcoming TROPOMI specifications – full physics method). CH₄ column (GEO): 4 × 4 km² horizontal resolution; hourly observations; precision = 1.0% (GEO-CAPE specifications) Both TROPOMI and GEO-CAPE may be able to resolve large point sources on daily scales.	Passive instruments give global coverage of columns (e.g., SCIAMACHY), but stymied by clouds and low light conditions. Emissions estimated from a model using satellite-observed methane and proxies (e.g., inundation depth) for emissions.	POR-10 (GOSAT, GOSAT2), POR-11 (TROPOMI)	TO-6
		Important	CH₄ (methane) concentration	Active: pencil pixel size; along track coverage, precision = 1.0% (specifications for upcoming MERLIN)	Active lidar instruments give data in regions that passive instruments cannot, such as night, low light and/or cloudy environments (e.g., monsoons, Arctic).	POR-2 (MERLIN)
QUESTION W-9. Role of Cloud Microphysical Processes. What processes determine cloud microphysical properties and their connections to aerosols and precipitation?	W-9a. Characterize the microphysical processes and interactions of hydrometeors by measuring the hydrometeor distribution and precip rate to within 5%.	Important	3D hydrometeor concentration and drop size distribution	0.5 g/kg	Microwave, IR		TO-5
			Vertical temperature profile	Horizontal resolution: 3 km; 1 km vertical; refresh; global 90 minutes, CONUS 60 minutes.	Microwave and IR sounders, GNSS-RO	POR-1, 6, 23	TO-13
			Vertical water vapor profile	Horizontal resolution: 3 km; 1 km vertical; refresh; global 90 min CONUS 60 minutes.	Microwave and IR sounders, GNSS-RO	POR-23	TO-13
			Vertical profiles of horizontal wind vector	Horizontal resolution: 3 km; 1 km vertical; refresh; global 90 minutes and CONUS 60 minutes.	Doppler wind lidar, AMVs from IR, WV and visible imagers and sounders		TO-13
			Precipitation rate	1 mm/hr accuracy; 2 km horizontal resolution; 1 min temporal refresh over a 20-30 min period.			TO-5
			Aerosol concentration	Aerosol optical depth (300 m resolution)	Nadir and multiangle radiometers (MODIS, MISR), lidars (CALYPSO, HRSL), Sun photometers (ground based) for calibration/validation.	POR-1, 2, 4, 10, 12	TO-2, TO-1
QUESTION W-10. Clouds and Radiative Forcing. How do clouds affect the radiative forcing at the surface and contribute to predictability on time scales from minutes to subseasonal?	W-10a. Quantify the effects of clouds of all scales on radiative fluxes, including on the boundary layer evolution. Determine the structure, evolution and physical/dynamical properties of clouds on all scales, including small-scale cumulus clouds.	Important	High-resolution 2D cloud fraction, helpful to also have estimates of cloud depth, and cloud droplet distribution; Ground-based radiation, water vapor, horizontal and vertical winds, temperature; Hydrometeors, temperature, moisture, winds from the boundary layer through the troposphere and into the UTLS; 3D aerosols, hydrometeors, vertical and horizontal winds, water vapor, temperature, precipitation.	Within 2% for cloud fraction over a 5 × 5 km area; spatial resolution 200 m desirable.	High-resolution visible/IR	POR-1, 11, 21, 23, 24

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

MARINE AND TERRESTRIAL ECOSYSTEMS AND NATURAL RESOURCES MANAGEMENT PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
QUESTION E-1. Ecosystem Structure, Function, and Biodiversity. What are the structure, function, and biodiversity of Earth’s ecosystems, and how and why are they changing in time and space?	E-1a. Quantify the distribution of the functional traits, functional types, and composition of vegetation and marine biomass, spatially and over time.	Very Important	Chemical properties of vegetation, aquatic biomass, and soils	Land, inland aquatic, costal zone, and shallow coral reef: Spectral radiance (10 nm; 380-2500 nm); GSD = 30-45 m; Revisit = ~15 days; SNR = 400:1 VNIR/250:1 SWIR at 25% reflectance; IT of ~5 ms. Ocean: Spectral radiance (5 nm; 380-1050 nm); GSD = 0.25-1.0 km; Revisit = <2 days; SNR = 1000:1 at TOA clear sky ocean radiance (PACE)	High-fidelity imaging spectrometer (150-200 km swath from Sun-synchronous LEO). For ocean, imaging spectrometer with wider swath and larger pixels.	Landsat-8 and -9 plus ESA Sentinal-2a, -2b, -2c, and -2d missions 30 m multispectra 3-4 day equatorial revisit frequency POR complement TO-18. PACE for ocean.	TO-18
		Very Important		Western hemisphere coastal ocean, inland waters: Geostationary; 100-300 m; 5-10 nm; 2-3 hr repeat; GSD = ~250 m	GEO spectrometers (e.g., GEO-CAPE)		TO-3
	E-1b. Quantify the three-dimensional (3D) structure of terrestrial vegetation and 3D distribution of marine biomass within the euphotic zone, spatially and over time.	Most Important	3D physical structure of vegetation and aquatic biomass	Land: Imaging waveform acquired in swaths; desired sampling = 1 ha cells with 10-25 m footprint size; global sampling every 5 years. Ocean: ~2 m vertical resolution subsurface to ~3 optical depths; High spectral resolution lidar (or similar) technique to retrieve vertical particle backscatter and vertical extinction profiles; ≤1 km footprint at sea surface; global	Imaging lidar (Land: 1064 nm; Ocean: 532 nm and 355 nm). NOTES: GEDI to deploy in 2019 for two years of canopy structure and biomass sampling; Synergy with ICESat-2 (not ideal for land vegetation) to launch circa 2020; Synergy with NISAR radar mission launches in 2022; Synergy with BIOMASS P-band mission to launch in 2020.		TO-22 and TO-20 for land lidar; TO-1 if it meets specs for ocean and TO-10 lidar
	E-1c. Quantify the physiological dynamics of terrestrial and aquatic primary producers.	Most Important	Primary Observable: Chemical properties of vegetation and aquatic biomass, and soils	Land, inland aquatic, coastal zone, and shallow coral reef: Spectral radiance (10 nm; 380-2500 nm); GSD = 30-45 m; Revisit = ~15 days; SNR = 400:1 VNIR/250:1 SWIR at 25% reflectance; IT of ~5 ms. Ocean: Spectral radiance (5 nm; 380-1050 nm); GSD = 0.25-1.0 km; Revisit = <2 days; SNR = 1000:1 at TOA Clear sky ocean radiance (PACE)	High-fidelity imaging spectrometer (150-200 km swath from sun-sync LEO). For ocean, imaging spectrometer with wider swath and larger pixels.	Landsat-8 and -9 plus ESA Sentinal-2a, -2b, -2c, and -2d missions 30 m multispectra 3-4 day equatorial revisit frequency. For ocean, PACE plus BioArgo (in situ).	TO-18
			Supporting observable: Solar-induced fluorescence	400-790 nm; 0.3 nm bandwidth (FWHM)	SIF spectrometer. NOTES: SIF sensors are in orbit and are planned, but require other measurements for interpretation. Science community indicates the need for concurrent imaging spectrometer (hyperspectral) and lidar measurements	GOME-2 POR and assume GEOCARB and FLEX will also be POR GEDI as POR lidar	TO-18
			Supporting observable: Thermal IR imaging	8-12 microns (cloudband at 1.6 microns); multispectral; GSD = 50-100 m; revisit = <15 days; day and night measurements. 150-200 km swath from Sun-synchronous LEO.	TIR imager (e.g., Landsat TIR). NOTES: Needs to be coupled with the spectrometer to determine physiology (including ET).	Landsat-8 and 9, MODIS, VIIRS plus ECOSTRESS are POR	TO-17
			Water particles for biomass accounting	Western Hemisphere Coastal Waters; Geostationary; 100-300 m; 5-10 nm; 2-3 hr repeat; GSD = ~250 m	GEO spectrometers (e.g., GEO-CAPE)		TO-3
			Net radiation and temperature for ET	Geostationary	Net radiation (e.g., GOES)	NOAA GOES-16 and GOES-S is POR

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

MARINE AND TERRESTRIAL ECOSYSTEMS AND NATURAL RESOURCES MANAGEMENT PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
	E-1d. Quantify moisture status of soils.	Important	Soil moisture	Combined radar (L-, P-band) and radiometer	Soil moisture (e.g., SMAP, SMOS)	SMAP, SMOS	TO-17
	E-1e. Support targeted species detection and analysis (e.g., foundation species, invasive species, indicator species, etc.).	Important	Plant species and/or aquatic biomass classification	Land, inland aquatic, costal zone, and shallow coral reef: Spectral radiance (10 nm; 380-2500 nm); GSD = 30-45 m; Revisit = ~15 days; SNR = 400:1 VNIR/250:1 SWIR at 25% reflectance; IT of ~5 ms. Land: Lidar; 1064 nm; Imaging waveform acquired in swaths; desired sampling = 1 ha cells with 10-25 m footprint size; global sampling every 5 years.	High-fidelity imaging spectrometer (150-200 km swath from LEO, e.g., VSWIR or HyspIRI)	Landsat-8 and -9 plus ESA Sentinal-2a, -2b, -2c, and -2d missions 30 m multispectra 3-4 day equatorial revisit frequency POR and complement TO-18 for plant functional types	TO-18
				Open Ocean, Land Vegetation mapping: Spectral radiance (5 nm; 380-1050 nm); GSD = 0.25-1.0 km; Revisit = <2 days; SNR = 1000:1 at TOA clear sky ocean radiance (PACE).	High-fidelity imaging spectrometer (1500-2000 km swath from LEO, e.g., PACE)	SeaWiFS, MODIS, VIIRS and Sentinel-3 (all at reduced spectral resolution) and PACE	TO-10
				Western hemisphere coastal waters:Geostationary; 100-300 m; 5-10 nm; 2-3 hr repeat; GSD = ~250 m	GEO spectrometers (e.g., GEO-CAPE)		TO-3
QUESTION E-2. Fluxes Between Ecosystems, Atmosphere, Oceans, and Solid Earth. What are the fluxes (of carbon, water, nutrients, and energy) between ecosystems and the atmosphere, the ocean, and solid Earth, and how and why are they changing?	E-2a. Quantify the fluxes of CO₂ and CH₄ globally at spatial scales of 100 to 500 km and monthly temporal resolution with uncertainty <25% between land ecosystems and atmosphere and between ocean ecosystems and atmosphere.	Most Important	Active and passive observations of atmospheric CO₂, CH₄, and CO concentrations	High accuracy column measurements with near-surface sensitivity, Global coverage in all seasons with 1-3 day revisit, Footprint resolution of ≤4 km CO₂: random error <1 ppm, systematic error <0.2 ppm CH₄: random error <10 ppb, systematic error <0.5 ppb CO: random error <10 ppb	Active and/or passive NIR observations for total column CO2, CH₄; TIR/SWIR observations of CO	GOSAT, GOSAT-2, OCO-2, OCO-3, GeoCARB, TEMPO, TROPOMI aboard Sentinel-5p	TO-6
			GPP, respiration, and decomposition, and biomass burning	Global, daily, 30 m / 300 m	Possible: VIIRS, Landsat, lidar topography, commercial sat data	Landsat-8 and -9 plus ESA Sentinal-2a, -2b, -2c, and -2d missions 30 m multispectra 3-4 day equatorial revisit frequency POR	TO-6 and TO-18
			3D winds	Global, daily, 5 km	Lidar winds		TO-4
			Air-sea delta pCO2 and air-sea gas transfer coef	global/daily, ≤100 km (less if apprp)	Possible: VIIRS, Aquarius FO, QuikSCAT FO	VIIRS, QuikSCAT
	E-2b. Quantify the fluxes from land ecosystems between aquatic ecosystems.	Important	Riverine transport of nutrients, organic matter and other constituents to oceans and inland waters	River discharge, water quality (POC, DOC, nutrients, CDOM, turbidity); high revisit (2-3 days)	Possible: MODIS, VIIRS, Landsat, Sentinel-2 water quality	MODIS, VIIRS, Landsat, Sentinel-2 water quality	TO-3
	E-2c. Assess ecosystem subsidies from solid Earth.	Important	Dust inputs, soil erosion, landslides, black carbon	High spatial resolution (1 m), bare-Earth topography at 0.1 m vertical accuracy Spectral radiance (10 nm; 380-2500 nm); GSD = 30-45 m	Aircraft lidar; VSWIR	MISR
QUESTION E-3. Fluxes Within Ecosystems. What are the fluxes (of carbon, water, nutrients, and energy) within ecosystems, and how and why are they changing?	E-3a. Quantify the flows of energy, carbon, water, nutrients, and so on, sustaining the life cycle of terrestrial and marine ecosystems and partitioning into functional types.	Most Important	GPP, respiration, litterfall and decomposition, nonPS vegetation, functional types	Global, daily, 30 m / 300 m Daily SIF measurements	MODIS, VIIRS, Landsat, lidar topography, commercial sat data SIF from GOSAT, GOME-2, and FLEX	Landsat-8 and -9 plus ESA Sentinal-2a, -2b, -2c, and -2d missions 30 m multispectra 3-4 day equatorial revisit frequency POR GOSAT and GOME-2	TO-18 and TO-20
		Most Important	CO₂, CO, CH₄, etc. fluxes from biomass burning	Global. Daily, 300 m.	e.g., {Sentinel-3} MODIS and VIIRS	MODIS and VIIRS POR	TO-6

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

MARINE AND TERRESTRIAL ECOSYSTEMS AND NATURAL RESOURCES MANAGEMENT PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			ET and root zone moisture	Globally, weekly, ~50 km.	Soil moisture (e.g., SMAP, SMOS, HDO from TES)	SMAP, TES	TO-17
			Aquatic NPP, PhytoC and Chl, NCP, Export from the euphotic zone, N₂ fixation and calcification, partitioned into functional types	Hyperspectral with spatial resolution 1 km and 1-2 day revisit for open ocean (PACE). Multi-spectral regional imaging with <200 m spatial resolution and <1 day revisit for coastal and inland waters (GEO-CAPE).	Imaging spectrometer (e.g., PACE, VIIRS); In situ ocean measurements and modeling; high-fidelity imaging spectrometer (150-200 km swath from Sun-synchronous LEO) for aquatic and coastal waters.	MODIS, VIIRS, PACE, Sentinel-3, Landsat-8 and -9 plus ESA Sentinal-2a, -2b, -2c, and -2d missions 30 m multispectra 3-4 day equatorial revisit frequency POR	TO-3 and TO-18
	E-3b. Understand how ecosystems support higher trophic levels of food webs.	Important	Rates of herbivory on terrestrial vegetation	See E-2a and E-3a	See E-2a and E-3a
		Important	Zooplankton population dynamics and secondary production	Modeling plus new sensor concept, possibly lidar.
*QUESTION E-4.* How is carbon accounted for through carbon storage, turnover, and accumulated biomass? Have all of the major carbon sinks been quantified and how are they changing in time?	E-4a. Improve assessments of the global inventory of terrestrial C pools and their rate of turnover.	Important	Aboveground carbon density (biomass)	Global, daily 30 m / 300 m lidar; 1064 nm; Imaging waveform acquired in swaths; desired sampling = 1ha cells with 10-25 m footprint size; global sampling every 5 years.	GEDI, ICESat-2, Landsat-8, Sentinel-2, MODIS, VIIRS		TO-20 and TO-22
		Important	Terrestrial GPP, respiration, decomposition and biomass burning	See E-2a and E-3a	See E-2a and E-3a		TO-6 and TO-18
	E-4b. Constrain ocean C storage and turnover.	Important	Air-sea CO2 fluxes	Hyperspectral with spatial resolution 1 km and 1-2 day revisit for open ocean.	NPP for biological contribution	PACE
	E-4b. Constrain ocean C storage and turnover.	Important	Vertical profile of export flux and water mass ventilation ages	Hyperspectral with spatial resolution 1 km and 1-2 day revisit for open ocean.	NPP (see above) plus in situ measurements (e.g., ARGO) and particle flux modeling.	PACE (for NPP)	TO-3 and TO-10
QUESTION E-5. Carbon Sinks. Are carbon sinks stable, are they changing, and why?	E-5a. Discover ecosystem thresholds in altering C storage.	Important	Roles of temperature and moisture, changes in community structure (incl. invasives), sea-level rise, ocean upwelling, etc. on C storage	See E-1 through E-4	Imaging spectrometer (e.g., PACE, MODIS, VIIRS); In situ ocean measurements and modeling	MODIS, VIIRS, PACE, Sentinel-3, Landsat-8 and -9 plus ESA Sentinal-2a, -2b, -2c, and -2d missions 30 m multispectra 3-4 day equatorial revisit frequency POR	TO-22 and TO-20 for land Lidar; TO-1 if it meets specs for ocean and TO-10 lidar
	E-5b. Discover cascading perturbations in ecosystems related to carbon storage.	Important	Cascading ecological perturbations (e.g., pine beetles, plankton or algal blooms, permafrost thawing, wildfire)	Hyperspectral with spatial resolution 1 km and 1-2 day revisit for open ocean.	Imaging spectrometer (e.g., PACE, MODIS, VIIRS); In situ ocean measurements and modeling	MODIS, VIIRS, PACE, Sentinel-3, Landsat-8 and -9 plus ESA Sentinal-2a, -2b, -2c, and -2d missions 30 m multispectra 3-4 day equatorial revisit frequency POR	TO-3, TO-18, TO-20, and TO-22
	E-5c. Understand ecosystem response to fire events.	Important	Wild and prescribed fires including active fire and burn area detection, GPP; 3D physical structure of vegetation; Chemical properties of vegetation	Global. Daily, 300 m.	Active fire detection using MODIS; VIIRS and the proposed TIR mission; (same as in E-1c but with eight bands); Burn area assessment using Landsat and Sentinel-2, MODIS, VIIRS and the proposed VSWIR imaging spectrometer (400 to 2500 nm) (same as in E-1e); Vegetation structure/fuel load assessment using lidar (same as in E-1b), SAR (Sentinel 1), and black carbon/smoke using CALIPSO, GEDI, GLAS, ICESat-1/2	Landsat-8 and -9 plus ESA Sentinal-2a, -2b, -2c, and -2d missions 30 m multispectra 3-4 day equatorial revisit frequency POR	TO-2, TO-6, TO-12, TO-18, and TO-22

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
QUESTION C-1. Sea-level Rise: Ocean Heat Storage and Ice Melt. How much will sea-level rise, globally and regionally, over the next decade and beyond, and what will be the role of ice sheets and ocean heat storage?	C-1a. Determine the global mean sea-level rise to within 0.5 mm/yr over the course of a decade.	Most Important	Sea-surface height	Space/Time Sampling: 7 km along track/10 day; Space/Time Coverage: global/10 days; Accuracy/Stability: 3 cm at 7 km and 1 mm/global/yr	Radar altimeter, with microwave water vapor radiometer and precision orbit	POR-26, 27	TO-21
			Terrestrial reference frame	Space/Time Sampling: monthly; Space/Time Coverage: global/year-decade; Accuracy/Stability: 1 mm/0.1 mm/yr/decade	GNSS RO	POR-7, 13 (GRACE-FO, Jason-3, LAGEOS, GRASP)
			Ocean mass distribution	Space/Time Sampling: 300 km²/monthly; Space/Time Coverage: global/monthly; Accuracy/Stability: 15 mm at 300 km², 0.1 mm/yr/decade	Gravity (e.g., GRACE FO)	POR-30	TO-9
	C-1b. Determine the change in the global oceanic heat uptake to within 0.1 W/m² over the course of a decade.	Most Important	Sea-surface height	Space/Time Sampling: 7 km along track/10 day, equivalent to 150 km²/10 day; Space/Time Coverage: global/10 days; Accuracy/Stability: 3 mm at 7 km, 1 mm/global/yr	Radar altimeter, with microwave water vapor radiometer and precision orbit	POR-26, 27	TO-21
			Ocean mass distribution	Space/Time Sampling: 300 km²/monthly; Space/Time Coverage: global/monthly; Accuracy/Stability: 15 mm at 300 km², 0.1 mm/yr/decade	Gravity (e.g., GRACE FO)	POR-30
			Ocean temperature and salinity profile	Space/Time Sampling: 3 degrees × 3 degrees/10 day, equivalent to 150 km²/10 day; Space/Time Coverage: global/10 days; Accuracy/Stability: 0.01 deg/0.01 psu	[in situ, such as Argo]	[Argo, Deep Argo]	TERRESTRIAL
	C-1c. Determine the changes in total ice-sheet mass balance to within 15 Gton/yr over the course of a decade and the changes in surface mass balance and glacier ice discharge with the same accuracy over the entire ice sheets, continuously, for decades to come.	Most Important	Ice-sheet mass	Horizontal resolution/range: 100 km / Global; Temporal sampling: Monthly; Precision: 1 cm water equivalent on scale of 200 km	Gravity (e.g., GRACE FO), NISAR/Landsat, [reanalysis], Operation IceBridge.	POR-30
			Ice-sheet velocity	Horizontal resolution/range: 100 m / pole to pole; Temporal sampling: weekly to daily; Precision: 1 m/yr in fast flow areas, 1 cm/yr near ice divides	SAR (e.g., NISAR), Landsat	POR-12	TO-19
			Ice-sheet elevation	Vertical resolution/range: 10-20 cm; Horizontal resolution/range: 100 m/pole to pole; Temporal sampling: weekly to daily; Precision: 10-20 cm	Operation IceBridge, ICESat-2, {WorldView satellites}, GLISTIN	POR-14	TO-20
			Ice-sheet thickness, ice-shelf thickness	Vertical resolution/range: 10 m pole to pole; Horizontal resolution/range: 100 m/pole to pole; Temporal sampling: yearly; Precision: 10 m	Operation IceBridge, ICESat-2 (ice shelf), {WorldView satellites}	POR-14	TO-20
			Ice-sheet bed elevation, ice-shelf cavity shape	Vertical resolution/range: 30 m; Horizontal resolution/range: 100 m/pole to pole; Temporal sampling: one time; Precision: 30 m	Operation IceBridge, EVS-2 OMG, new EVS Antarctica		TO-20
			Ice-sheet surface mass balance	Vertical resolution/range: 1 mm/yr; Horizontal resolution/range: 5 km/pole to pole; Temporal sampling: monthly; Precision: 1 mm/yr	Gravity (e.g., GRACE FO), ICESat-2, Operation IceBridge, [re-analysis data]	POR-14, 30	TO-20
	C-1d. Determine regional sea-level change to within 1.5-2.5 mm/yr over the course of a decade (1.5 corresponds to a	Very Important	Sea-surface height	Space/Time Sampling: 250 m/weekly at midlatitudes; Space/Time Coverage: 20 days/global; Accuracy: 10 cm	e.g., SWOT to be launched 2021		TO-21

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
	~6000 km² region, 2.5 corresponds to a ~4000 km² region).		Land vertical motions	Space/Time Sampling: 100 m along coast; Space/Time Coverage: global coastline/monthly; Accuracy/stability: 1 mm/1 mm/yr	[ground GPS]		TERRESTRIAL
			Ocean mass distribution	Same as C-1a		POR-30
			Wind vector	Space/Time Sampling: 25 × 25 km/weekly; Space/Time Coverage: global/weekly; Accuracy/stability: 2 m/s speed, 15 degree direction	METOP A/B, Oceansat-3, HY-2B	POR-28	TO-11
QUESTION C-2. Climate Feedback and Sensitivity. How can we reduce the uncertainty in the amount of future warming of Earth as a function of fossil fuel emissions, improve our ability to predict local and regional climate response to natural and anthropogenic forcings, and reduce the uncertainty in global climate sensitivity that drives uncertainty in future economic impacts and mitigation/adaptation strategies?	C-2a. Reduce uncertainty in low and high cloud feedback by a factor of 2.	Most Important	Top of Atmosphere Shortwave (SW), Longwave (LW) and Net Radiative Fluxes for All-sky and Clear-sky conditions	Space/Time Sampling: 100 km, monthly; Space/Time Coverage: global, decadal trends; Accuracy/Stability: global SW TOA flux at 0.3% (95% confidence), global LW TOA flux at 0.6% (95% confidence); Ultimate requirement is on use for Cloud Radiative Effect for SW and LW	Earth radiation monitor (e.g., CERES), RBI for space-time-angle sampling, CLARREO-like intercalibration (to achieve decadal trend accuracy/stability)	POR-3, 24	TO-14
			Cloud fraction	Space/Time Sampling: 100 km, monthly; Space/Time Coverage: global, decadal trends; Accuracy/Stability: 0.1% relative to global mean (1σ)	Cloud imagers (e.g., MODIS/VIIRS), or lidar (e.g., CALIPSO) or HSRL	POR-24	TO-2
			Cloud optical depth	Space/Time Sampling: 100 km, monthly; Space/Time Coverage: global, decadal trends; Accuracy/Stability: 0.3% relative to global mean log optical depth (95% confidence)	Cloud imagers (e.g., MODIS/VIIRS) plus CLARREO-like intercalibration (to achieve optical depth trend accuracy/stability)	POR-24	TO-14
			Cloud infrared emissivity	Space/Time Sampling: 100 km, monthly; Space/Time Coverage: global, decadal trends	Cloud imagers (e.g., MODIS/VIIRS), or lidar (e.g., CALIPSO) or HSRL	POR-24	TO-2 or TO-14
			Cloud top height	Space/Time Sampling: 100 km, monthly; Space/Time Coverage: global, decadal trends; Accuracy/Stability: 0.04 K (1σ)	Cloud imagers (e.g., MODIS/VIIRS) plus CLARREO-like intercalibration or lidar (e.g., CALIPSO) or HSRL	POR-24	TO-2 or TO-14
			Cloud effective radiating temperature	Space/Time Sampling: 100 km, monthly; Space/Time Coverage: global, decadal trends; Accuracy/Stability: 0.04 K (1σ)	Cloud imagers (e.g., MODIS/VIIRS) plus CLARREO-like intercalibration	POR-24	TO-2 or TO-14
			Cloud phase (water, ice)	Space/Time Sampling: 100 km, monthly; Space/Time Coverage: global, decadal trends	Cloud imagers (e.g., MODIS/VIIRS), or lidar (e.g., CALIPSO) or HSRL	POR-24	TO-14
			Cloud particle size	Space/Time Sampling: 100 km, monthly; Space/Time Coverage: global, decadal trends	Cloud imagers (e.g., MODIS/VIIRS) plus CLARREO-like intercalibration	POR-24	TO-14
	C-2b. Reduce uncertainty in water vapor feedback by a factor of 2.	Very Important	Atmospheric water vapor and temperature profiles	Vertical Resolution/Coverage: 2 km from 0 to 15 km altitude; Space/Time Sampling: 100 km horizontal resolution/monthly average Time/Space Coverage: decadal trends/global; Accuracy/Stability: 0.03 K (1σ)	IR sounders (e.g., CrIS, IASI) plus CLARREO-like intercalibration, GNSS-RO for zonal temperature trend in 5-20 km altitude	POR-6, 20	TO-14
	C-2c. Reduce uncertainty in temperature lapse rate feedback by a factor of 2.	Very Important	Atmospheric temperature profile	Vertical Resolution/Coverage: 2 km from 0 to 15 km altitude; Space/Time Sampling: 2 km vertical resolution, 100 km horizontal resolution/monthly Time/Space Coverage: decadal	IR sounders (e.g., CrIS, IASI) plus CLARREO-like intercalibration, GNSS-RO for zonal temperature trend in 5-20 km altitude	POR-6, 20; Suborbital: Global Climate Observing System Reference Upper-Air Network (GRUAN), NWS Upper-Air Observations Program	TO-14

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
				trends/global; Accuracy/Stability: 0.03 K (1σ)
	C-2d. Reduce uncertainty in carbon cycle feedback by a factor of 2.	Most Important	See Objectives C-3a, C-3c, C-3d, and C-3e	See Objective C-3a, C-3c, and C-3e
	C-2e. Reduce uncertainty in snow/ice albedo feedback by a factor of 2.	Important	Surface Snow and Ice Coverage	Space/Time Sampling: 10 km horizontal resolution/monthly average; Time/Space Coverage: decadal trends regional and global; Accuracy/Stability: 1% (1σ)	MODIS/VIIRS for snow/ice cover and surface albedo. CERES for TOA albedo	POR-3, 24
		Important	Surface albedo and Top of Atmosphere albedo (spectral and broadband)	Space/Time Sampling: 100 km horizontal resolution/monthly average; Time/Space Coverage: decadal trends regional and global; Accuracy/Stability: 1% (1σ)	MODIS/VIIRS for snow/ice cover and surface albedo. CERES for TOA albedo	POR-3, 24
	C-2f. Determine the decadal average in global heat storage to 0.1 W/m² (67% confidence) and interannual variability to 0.2 W/m² (67% confidence).	Very Important	Same as for Objective C-1b		See Objective C-1b	POR-3, 24
			Global net radiation	Space/Time Sampling: 100 km, monthly; Space/Time Coverage: Monthly to decadal, Global; Interannual stability/drift of calibration less than 0.1 W/m²	Earth radiation monitor (e.g., CERES), RBI for space-time-angle sampling, CLARREO-like intercalibration (to achieve decadal trend accuracy/stability)	POR-3, 24	TO-14
			Total solar irradiance	Space/Time Sampling: full solar disk, daily; Space/Time Coverage: monthly to decadal; Accuracy/Stability: 0.01%/0.01% per decade	Total solar irradiance (e.g., TSIS)	TSIS on ISS, JPSS
	C-2g. Quantify the contribution of the upper troposphere and stratosphere (UTS) to climate feedbacks and change by determining how changes in UTS composition and temperature affect radiative forcing with a 1-sigma uncertainty of 0.05 W/m² over the course of the decade.	Very Important	Vertical profiles of temperature in UTS (upper troposphere and stratosphere), for quantifying radiative forcing	Vertical resolution and range: <1 km in UTLS, <3 km in mid-upper stratosphere; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: weekly; Precision: 1-2 K.	UV, visible, and infrared solar, lunar, and stellar occultation (e.g., ACE-FTS, GOMOS, HALOE, POAM, SAGE) High precision, high vertical resolution (<1 km), climate (trend) quality, but poor spatial coverage unless using a constellation. Infrared and microwave limb emission (e.g., HIRDLS, MIPAS, MLS, Odin SMR) Many species, 3-4 km vertical resolution, night and day, global coverage Visible limb scattering (e.g., SME, OMPS-LP, OSIRIS) Lidar (e.g., CALIPSO-CALIOP) High (meters) vertical resolution Radar (e.g., CloudSat CPR) Nadir-viewing solar reflection/scattering (e.g., AIM-CIPS, MODIS, OCO-2) Good (km) horizontal resolution	POR-6, 16, 17, 18 ACE-FTS (not global), Auro MLS (not 1 km verical resolution; not self-calibrating), GPS-RO (extreme path length), MSU/SSU/AMSU (10 km vertical resolution; not self-calibrating)	TO-13
			Vertical profiles of radiatively active gas concentrations in the UTS, for quantifying radiative forcing	Concentration of O3: Vertical resolution and range: <1 km in UTLS, <3 km in mid-upper stratosphere; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: weekly; Precision: 10%. Concentration of H2O: Vertical resolution and range: <1 km in UTLS, <3 km in mid-upper stratosphere; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: weekly; Precision: 10%.		POR-6, 16, 17, 18 ACE-FTS (not global; not 1 km vertical resolution), Aura MLS (not 1 km vertical resolution; not self-calibrating), OMPS-L (not 1 km vertical resolution; not self-calibrating (?)); Suborbital measurements: Network for the Detection of Atmospheric Composition Change, Global Climate Observing System Reference Upper-Air Network (GRUAN), Southern Hemisphere Additional Ozonesondes (SHADOZ) SAGE III (ISS) (not global; 18 Feb 2017 launch)	TO-12

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			Vertical profiles of UTS aerosol radiative properties, for quantifying radiative forcing	Vertical resolution and range: <1 km in UTLS; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: weekly; Precision: 30%.		POR-2, 16, 18 ACE-FTS [not global; not 1 km vertical resolution], Odin OSIRIS [not 1 km vertical resolution; not polar night; no particle size info], CALIPSO CALIOP [near end-of-life] SAGE III (ISS) [not global]	TO-1, TO-2
			Volcanic and biomass burning emissions, for process studies (sources and transport)	Volcanic Aerosol: Vertical resolution and range: <1 km in UTLS; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: daily during events; Precision: 30%. Concentrations of gases from volcanic emissions: Vertical resolution and range: <1 km in UTLS; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: daily during events; Precision: ~20%, but species dependent.		POR-2, 16, 17, 18 Volcanic Aerosol: CALIPSO CALIOP [near end-of-life] Concentrations of gases from volcanic emissions: ACE-FTS [not global; not 1 km vertical resolution], MLS [not 1 km vertical resolution; not NO₂] SAGE III (ISS) [not enough sampling to track the sources]	TO-1, TO-2, TO-12
			Deep convective clouds, for process studies (sources)	Vertical resolution and range: <1 km in UTLS; Horizontal range: Global; Horizontal and temporal sampling: event-specific, episodic; Precision: 30%.		POR-1, 4, 10, 17, 21, 23 Aura MLS (not 1 km vertical resolution), Aqua AIRS, Aqua AMSR-E, Aqua MODIS, CloudSat	TO-5
			Small-scale transport and the Brewer-Dobson circulation, for process studies (transport)	Vertical resolution and range: <1 km in UTLS, <3 km in mid-upper stratosphere; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: event-driven for small scale, weekly for BD; Precision: 30%.		POR-16, 17 ACE-FTS [not global; not 1 km vertical resolution], Aura MLS [not 1 km vertical resolution]	TO-12, TO-13
			Dynamical features such as the polar vortex, for process studies (transport)	Vertical resolution and range: <1 km in UTLS, <3 km in mid-upper stratoshpere; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: daily to weekly; Precision: 1-2 K (T), 30% (UV).		POR-6, 16, 17, 18 ACE-FTS [not global; not 1 km vertical resolution], Aura MLS [not 1 km vertical resolution], GPS-RO [extreme path length]	TO-12, TO-13
			Planetary and gravity waves, for process studies (transport)	Vertical resolution and range: <1 km from cloud top to stratopause; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: daily to weekly; Precision: 1-2 K (T).		POR-6, 16, 17, 18 ACE-FTS [not global; not 1 km vertical resolution], Aura MLS [not 1 km vertical resolution], GPS-RO [extreme path length]	TO-12, TO-13
			Stratospheric ozone and related constituents, for process studies (chemistry)	Vertical resolution and range: <1 km from cloud top to stratopause; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: daily to weekly; Precision: 5% (O₃), 10% (others).		POR-16, 17, 18 ACE-FTS [not global; not 1 km vertical resolution], Aura MLS [not 1 km vertical resolution; only some of the constituents]); Suborbital measurements: Network for the Detection of Atmospheric Composition	TO-12

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
						Change, Global Climate Observing System Reference Upper-Air Network (GRUAN), Southern Hemisphere Additional Ozonesondes (SHADOZ) SAGE III [not global; only some of the constituents]
	C-2h. Reduce the IPCC AR5 total aerosol radiative forcing uncertainty by a factor of 2.	Most Important	AEROSOLS. Aerosol Size (0.05 μm and larger), vertical profiles of mass concentrations (10/cm³ and greater), effective radius. Also needed: (1) column properties (aerosol optical depth, burden as aerosol mass concentration), (2) plume properties (e.g., characterizing aerosol type, plume height, and plume thickness), and (3) characteristics at cloud base. Physical properties: (1) ability to distinguish size of those aerosols most important to become cloud condensation nuclei (CCN, 0.1 μm radius and smaller), from those most radiatively active (0.5 μm and larger), (2) aerosol source/chemical composition, (3) hygroscopicity, Need to separate absorption from total extinction, and obtain vertical profiles of both extinction and absorption, as well as relative humidity.	Horizontal resolution requirements: at high (1 km) to very high (<100 m); Vertical resolution requirement: Information is needed at low (column integrals) and high (<500 m) resolution. Temporal sampling: weekly; Precision: 30%. Accuracy requirements: vertically and horizontally resolved aerosol number and mass concentration (100%), effective variance (50%), and effective radius (10%) over the 0.1 to 1 μm radius range. Vertical distribution of temperature (0.2°C), humidity (uncertainty 0.3 g/kg).	Nadir viewing radiometers (e.g., MODIS); Multiangle viewing radiometers (MISR); Current technology lidar (CALIPSO); More modern technology lidar (HSRL); HSRL can be used for vertically resolved profiles that better enable (1) distinguishing aerosols and clouds, (2) increased sensitivity (detecting lower concentrations of aerosol), (3) better resolution of aerosol amounts nearer the surface (lower altitude), and (4) more accurate aerosol optical depths. Multiangle, multispectral polarimeters can provide improved column integrated information on aerosol composition such as refractive index (including absorption), particle size, and variance. The combination of HSRL and a multiangle, multispectral polarimeter has improved accuracy beyond each individual instrument.	POR-1, 2, 5, and Terrestrial. Also, POR-7, 13 (GRACE-FO, Jason-3, LAGEOS, GRASP)	TO-1, TO-2, TO-12, TO-18, TO-20
			CLOUDS. Nearby (to aerosol fields) and simultaneous measurements of cloud properties (cloud water path, thickness, altitude, condensate phase, cloud particle size, anvil extent and thickness), and precipitation characteristics. Derive estimates (with uncertainty) of cloud base vertical motions and maximum updraft velocities in cloud. Lidar (e.g., CALIOP) to separate cloud and aerosol. Determine properties of the aerosol ingested into clouds and cloud systems, and obtain a sufficiently long and diverse (in cloud types and locations) record to enable statistical interpretation of aerosol-cloud interactions. Determine drizzle frequency and amount (e.g., CloudSat).	Determination of cloud height, cloud cover, microphysical properties. Horizontal resolution: 5 degrees latitude × 10 degrees longitude/Global. Temporal sampling: weekly. Precision: 30%. Improving the confidence levels through increased accuracy in various cloud fields: LWC 50% ->20% IWC 70% -> 20% Cloud thickness 240 -> 75 m Drizzle	Nadir and multi angular radiometers (MODIS, MISR); Lidars (CALIPSO, HSRL); W-band radar reflectivity profiles (e.g., CloudSat) that accounts for light rain/snow; microwave brightness temperatures; shortwave reflectances in the near IR and visible bands; stereo photogrammetric methods that build on and advance measurements pioneered by the MISR instrument on the Terra satellite.	POR-1, 2, 4, 5, 10, 20, 23, 24	TO-1, TO-2, TO-5, TO-13
			ENVIRONMENT. Meteorological properties in vicinity of aerosols	Atmospheric water vapor and temperature profiles: vertical	See C-12. IR sounders (e.g., CrIS, IASI) plus CLARREO-like	POR-5, 6, 7, 10, 20, 24	TO-1, TO-13, TO-14

Page 601 Cite Bookmark

Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			and clouds (temperature, winds, humidity) to characterize the environment in which the cloud is forming.	resolution/coverage: 2 km from 0 to 15 km altitude. Space/Time Sampling: 25 km horizontal resolution/monthly avg. Time/Space Coverage: decadal trends/global. Accuracy/Stability: 0.03 K (1σ) 3D Winds (see E-2, from Weather Panel, and C-3f) Surface winds (see C-4a): (U10, windspeed and direction) 20 km spatial resolution; 3 hr revisit; 0.5 m/s instantaneous uncertainty, 0.1 m/s monthly uncertainty, decadal stability to 0.05 m/s/decade; direction to 15 degrees instantaneous, monthly to 10 deg.	intercalibration, GNSS-RO for zonal temperature trend in 5-20 km altitude
QUESTION C-3. Carbon Cycle, Including Carbon Dioxide and Methane. How large are the variations in the global carbon cycle and what are the associated climate and ecosystem impacts in the context of past and projected anthropogenic carbon emissions?	C-3a. Quantify CO₂ fluxes at spatial scales of 100-500 km and monthly temporal resolution with uncertainty <25% to enable regional-scale process attribution explaining year-to-year variability by net uptake of carbon by terrestrial ecosystems (i.e., determine how much carbon uptake results from processes such as CO₂ and nitrogen fertilization, forest regrowth, and changing ecosystem demography.)	Very Important	Biomass and biomass change	See E-3a	See E-3a
			GPP, respiration, and decomposition, and biomass burning	See E-3a	See E-3a
			Atmospheric CO₂	Random error: XCO₂: goal = 1 ppm, threshold = 3 ppm; Systematic error: XCO₂: goal = 0.2 ppm, threshold = 0.5 ppm; Mission duration: 3‐5 years provides a snapshot of current conditions; Trends and interannual variability will require systematic measurements >10 yr	NearIR for total column plus thermal for separation of boundary layer and upper, ground-based and aircraft in situ measurements for linking to WMO calibration scales ground-truth	Orbital: POR-11 (OCO2, OCO-3-on-ISS), POR-24 (GOSAT, GOSAT-2), GeoCARB; Suborbital: NOAA Global Greenhouse Gas Reference Network, Total Carbon Column Observing Network	TO-6
			Solar-induced flourescence	See E-1c	Ecosystem Panel, European FLEX Mission 2020, GOME-2, OCO-2	POR-11, POR-32 (FLEX)
			Leaf Area Index, Enhanced Vegetation Index, Normalized Difference Vegetation Index	Similar to or better than MODIS
			Atmospheric CO	Similar to or better than MOPITT		POR-11, Geo-CARB	TO-6
	C-3b. Reliably detect and quantify emissions from large sources of CO₂ and CH₄, including from urban areas, from known point sources such as power plants, and from previously unknown or transient sources such as CH₄ leaks from oil and gas operations.	Important	Atmospheric CO₂ and/or CH₄	Geostationary or other mapping capability. Measurement comparability <0.2 ppm for CO₂ 0.5 ppb for CH₄ over time scales of decades will be needed to track changes in emissions. Spatial scale <1 km.	Geo or other mapping	Geo-CARB	TO-6
	C-3c. Provide early warning of carbon loss from large and vulnerable reservoirs such as tropical forests and permafrost.	Important	Atmospheric CO₂ and/or CH₄	Random error: XCO₂: goal = 1 ppm, threshold = 3 ppm; Systematic error: XCO₂: goal = 0.2 ppm, threshold = 0.5 ppm; Random Error: XCH₄ goal = 6 ppb, threshold = 12 ppb; Systematic error: goal = 2.5 ppb, threshold = 5 ppb	Geo or other mapping	POR-2 (ASCENDS, MERLIN), Geo-CARB	TO-6
		Important	Biomass change	See E-3a	See E-3a
	C-3d. Provide regional-scale process attribution for carbon uptake by ocean to within 25%	Important	Surface roughness—air sea gas transfer coefficient	See W-3a (i.e., ocean surface vector wind/surface wind stress)	See E-9
			Winds	See W-3a, E-2	(from Weather Panel)

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
	(especially in coastal regions and the Southern Ocean).		Atmospheric CO₂	Note ocean uptake signals of order 0.1 ppm and cannot be measured with current satellite sensor technology	No existing or proposed spaceborne XCO₂ sensor is capable of detecting ocean flux signals to enable useful flux quantification
			Ocean color	(from Ecosystem panel)	(from Ecosystem panel)	POR-21 (PACE), POR-24 (VIIRS)	TO-18
			Salinity	(from Ecosystems or Weather Panel)	(from Ecosystems or Weather Panel)	POR-23
	C-3e. Quantify CH₄ fluxes from wetlands at spatial scales of 300 km × 300 km and monthly temporal resolution with uncertainty better than 3 mg CH₄ m⁻² day⁻¹ in order to establish predictive process, based understanding of dependence on environmental drivers such as temperature, carbon availability, and inundation.	Important	CH₄ fluxes	Random Error: goal = 6 ppb threshold = 12 ppb; Systematic error: goal = 2.5 ppb, threshold = 5 ppb; Mission duration: 3‐5 years provides a snapshot of current conditions; Spatial coverage: Tropics, Boreal		POR-2 (MERLIN), POR-11 (TropOMI), GeoCARB	TO-6
	C-3f. Improve atmospheric transport for data assimilation/inverse modeling.	Important	3D Winds	See E-2	See W-1 and W-3
			PBL depth	See W-1	See W-1
			Convective transport	See W-4	See W-4
			Surface pressure	See W-2, to within 1 mb	See W-2		TO-5
	C-3g. Quantify the tropospheric oxidizing capacity of OH, critical for air quality and dominant sink for CH₄ and other GHGs.	Important	Abundance of gases lost by reaction with OH, such as HCFC-22, HFC-32 and HFC-152a	Vertical resolution and range: 1 km / mid-upper troposphere; Horizontal resolution/range: 50 km / global; Temporal sampling: Weekly; Precision: HCFC-22: ~10% (20 ppt), HFC-32: ~30% (3 ppt), HFC-152a: ~50% (4 ppt). Profiles of CO in the mid to upper global troposphere would provide useful information. This objective must have a strong suborbital component to be achieved.	There are the appropriate sample approaches: a) UV, visible, and infrared solar, lunar, and stellar occultation (e.g., ACE-FTS, GOMOS, HALOE, POAM, SAGE); b) Infrared and microwave limb emission (e.g., HIRDLS, MIPAS, MLS, Odin SMR).	Orbital: ACE-FTS, MLS, MOPITT, Odin SMR, SAGE III, TANSO-FTS. Suborbital: NASA ATom and other airborne surveys of tropospheric OH that include the tropical troposphere; continued ground-based observations of methyl chloroform and other well mixed gases with well defined emission source strength that are primarily lost by reaction with tropospheric OH.
QUESTION C-4. Atmosphere-Ocean Flux Quantifications. How will the Earth system respond to changes in air-sea interactions?	C-4a. Improve the estimates of global air-sea fluxes of heat, momentum, water vapor (i.e., moisture) and other gases (e.g., CO₂ and CH₄) to the following global accuracy in the mean on local or regional scales: (1) radiative fluxes to 5 W/m², (2) sensible and latent heat fluxes to 5 W/m², (3) winds to 0.1 m/s, and (4) CO₂ and CH₄ to within 25%, with appropriate decadal stabilities.	Very Important	Surface vector winds	(U10, windspeed and direction) 20 km spatial resolution; 3 hr revisit; 0.5 m/s instantaneous uncertainty, 0.1 m/s monthly uncertainty, decadal stability to 0.05 m/s/decade; direction to 15 degrees instantaneous, monthly to 10 degrees	Scatterometer, Doppler scatterometer, passive microwave, SAR (possible new versions based on GPM microwave imager, or Compact Ocean Wind Vector Radiometer; Vector winds highly desirable for momentum fluxes)	POR-28; SSM/I, SSM/IS, AMSR-2, GMI, MWI. Move POR-7 CYGNSS (Mission ID 740, Instrument ID 1669, Unique ID 740-1669) to POR-33	TO-11 (if scatterometer and tuned to stress)
			10 m air humidity and temperature and SST	(BL atmos) 20 km horizontal resolution; 500 m vertical resolution with 10 m at surface; 3 hr revisit; monthly 0.2°C uncertainty (temperature), 0.3 g/kg (humidity)	For temperature and humidity: IR and microwave sounders (e.g., AIRS, AMSU, ATMS), GNSS-RO	POR-1, (6)	TO-13
			Sea-surface temperature (skin)	0.2 K random uncertainty in 25 × 25 km area; 80% daily coverage; 3 to 5 km resolution.	IR or microwave radiometery	POR-23 AMSR-2 (Mission ID 459, Instrument ID 883, Unique ID 459-883) with caveats (see notes)
			Radiative fluxes	Global and regional bias of 5 W/m², spatial resolution of 25 km, temporal	Like CERES on Terra/Aqua	POR-3

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
				sampling 3 hr. Accuracy of 5 W/m², decadal stability of 0.3 W/m²/decade.
			Surface currents	An average of 1-2 samples (overpasses) per day per 100 to 200 km region for a high inclination orbit; 5 to 10 km resolution; Random errors ≤0.02 m/s for 100 km scales and 1 to 2 day averages (this is analogous to current random errors <0.5 m/s for the proposed sampling); Coincidence with vector wind observations.	Altimeter (e.g., Jason-3) or Doppler scatterometer for surface current
			Wave heights	(Hs, significant wave height) 25 km spatial resolution; 3 hr revisit; 0.5 m uncertainty	Altimeter (e.g., Jason-3) for significant wave height	POR-26, 27	TO-21
			XCO₂ and XCH₄ (dry air mole fraction of these species)	25% uncertainty monthly average
	C-4b. Better quantify the role of surface waves in determining wind stress; demonstrate the validity of Monin-Obukhov similarity theory and other flux-profile relationships at high wind speeds over the ocean.	Important	Wave heights	(Hs, significant wave height) 25 km spatial resolution; 3 hr revisit; 0.5 m uncertainty	(Hs, significant wave height) Jason altimeter	POR-26, 27	TO-21
			Surface layer profiles of temperature and humidity	(BL atmos) 20 km horizontal resolution; 10 m vertical resolution with 10 m at surface and near-surface; 3 hr revisit; monthly 0.2°C uncertainty (temperature), 0.3 g/kg (humidity)	(BL Atmos) For temperature and humidity: IR and microwave sounders (e.g., AIRS, AMSU, ATMS), GNSS-RO	POR-1	TO-13
			BL wind profiles	(U10, windspeed and direction) 20 km spatial resolution; 3 hr revisit; 0.5 m/s instantaneous uncertainty	(U10, windspeed or stress) Scatterometer, Doppler scatteroemter, passive microwave, SAR; possible new versions based on GPM microwave imager, or Compact Ocean Wind Vector Radiometer; Vector winds highly desirable for momentum fluxes	POR-23, 28, 33	TO-11 (if scatterometer and tuned to stress)
	C-4c. Improve bulk flux parameterizations, particularly in extreme conditions and high-latitude regions reducing uncertainty in the bulk transfer coefficients by a factor of 2.	Important	Turbulent heat fluxes: direct covariance flux estimates of latent and sensible heat flux and simultaneous independent measurements of surface layer air temperature and humidity, sea-surface temperature, surface-relative surface layer winds. Momentum flux: direct covariance flux estimates of stress and simultaneous independent measurements of surface layer air temperature, sea-surface temperature, surface-relative surface layer winds, directional wave spectra. Gas fluxes: direct covariance flux estimates of gas fluxes and measurements of surface layer air temperature, sea-surface temperature, surface-relative surface layer winds, and gas partial-	Accuracy: Direct covariance flux estimates 20% (stress), 30% uncertainty (heat, moisture, gases) on a point-by-point basis; Wind speed at 0.5 m/s instantaneous uncertainty; 0.2 K instantaneous uncertainty in surface layer air and sea-surface temperature; 0.3 g/kg instantaneous uncertainty in surface layer humidity; gas partial pressure difference to 4 μatm. Wave steepness data needs resolution of waves at 50 to 200 m wavelengths. Increased data needed at a variety of regimes: momentum/turbulent heat flux: wind speeds globally greater than 15 m/s; momentum/turbulent heat flux at stable conditions (air-sea temperature difference >2°C); momentum flux: measurements in strongly coupled swell-dominated regions; gas exchange at all wind speeds, all stability conditions; all wind speeds for gas exchanges. All momentum/heat/moisture/gas fluxes:	Satellite observations: improved drag coefficients: simultaneous but independent surface stess and wind speed measurements (e.g., scatterometer for stress; wind speeds from passive microwave, scatterometers; wave steepness from SAR. Other turbulent direct covariance fluxes needed for bulk flux parameterizations unobtainable from satellite. In situ: direct covariance flux measurements and simultaneous independent bulk measurements, wave information, for all fluxes from buoys, expendable platforms at sufficient elevation	Satellite: SAR, POR-(1), CFOSAT In situ: OceanSITES buoys, OOI buoys, ships of opportunity, towers, individu research experiments and associated assets	TO-11 (if scatterometer and tuned to stress) al

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO

			pressure gradients between atmospheric and ocean surface layers	measurements needed in marginal ice zone regions.
	C-4d. Evaluate the effect of surface CO₂ gas exchange, oceanic storage, and impact on ecosystems, and improve the confidence in the estimates and reduce uncertainties by a factor of 2.	Important	Surface CO₂ gas exchange: Wind speeds; partial pressure CO₂ in equilibrium with surface water air above	Surface CO₂ gas exchange: 25% uncertainty monthly average	Wind speeds: scatterometer, Doppler scatterometer, passive microwave, SAR CO₂ partial pressures: in situ measurements	POR-28; SSM/I, SSM/IS, AMSR-2, GMI, MWI. Move POR-7 CYGNSS (Mission ID 740, Instrument ID 1669, Unique ID 740-1669) to POR-33	TO-11
QUESTION C-5. Aerosols and Aerosol Cloud Interactions. A. How do changes in aerosols (including their interactions with clouds, which constitute the largest uncertainty in total climate forcing) affect Earth’s radiation budget and offset the warming due to greenhouse gases? B. How can we better quantify the magnitude and variability of the emissions of natural aerosols, and the anthropogenic aerosol signal that modifies the natural one, so that we can better understand the response of climate to its various forcings?	C-5a. Improve estimates of the emissions of natural and anthropogenic aerosols and their precursors via observational constraints.	Very Important	Vertical profiles of aerosol mass concentrations, and including particle size (effective radius). Boundary layer concentrations are most relevant for sources; vertical profiles are most relevant for removal processes (settling and precipitation removal). Also needed: (1) dust, smoke, and other aerosol plume properties (e.g., characterizing height and thickness), and (2) characteristics in the column to assess removal rates. Precipitation phases and rates. Surface properties: (1) soil moisture; (2) topography; (3) soil type and vegetation coverage; (4) ocean surface characteristics (bubbles, waves); (5) sea-surface temperature. Surface vector winds. Fire radiative power, vegetation type and plume lofting height for fire mass consumption rate, smoke properties and plume height. Aerosol precursor gases that include NO_x, SO₂, DMS, VOCs, NH₄, and co-emitted gases that include CO and CO₂.	Aerosol mass: Horizontal resolution requirements: at high (1 km) to very high (<100 m); Vertical resolution requirement: Information is needed at low (column integrals) and high (<500 m) resolution. Temporal sampling: weekly; Precision: 30%. Accuracy requirements: vertically and horizontally resolved aerosol mass concentration (100%) and effective variance (50%). (U10, windspeed and direction) 20 km spatial resolution; 3 hr revisit; 0.5 m/s instantaneous uncertainty, 0.1 m/s monthly uncertainty, decadal stability to 0.05 m/s/decade; direction to 15 degrees instantaneous, monthly to 10 degrees. (Hs, significant wave height) 25 km spatial resolution; 3 hr revisit; 0.5 m uncertainty. SST: 0.2 K random uncertainty in 25 × 25 km area; 80% daily coverage; 3 to 5 km resolution. Gas measurements: NO_x, SO₂, DMS, VOCs, NH₄, CO, and CO₂.	See C-2h for Aerosol Measurement Approaches, C-4a for air-sea exchange that includes these below, Ecosystem for vegetation, biomass burning, dust, and possibly gases C-40. Scatterometer, Doppler scatterometer, passive microwave, SAR (possible new versions based on GPM microwave imager, or Compact Ocean Wind Vector Radiometer; Vector winds highly desirable for momentum fluxes) SST: C-42. IR and/or microwave radiometry C-44B. Altimeter (e.g., Jason-3) for significant wave height	POR-2, 5, 7, 9, 10, 11, 12, 14, 20, 21, 22, 24, 25, 28, 32	TO-1, TO-2, TO-3, TO-4, TO-6, TO-10, TO-11, TO-15, TO-17, TO-18, TO-22
	C-5b. Characterize the properties and distribution in the atmosphere of natural and anthropogenic aerosols, including properties that affect their ability to interact with and modify clouds and radiation.	Important	AEROSOLS: (1) extinction, absorption, AOD, AAOD (spectrally resolved), polarization, single scattering albedo, (2) size and shape, (3) vertical and horizontal distribution, (4) hydroscopicity, composition (probably not from space implices need for ground and airborne help), (5) ancillary useful variables (CO, isoprene, relative humidity, etc.).	This is a refinement of Objective C-5a. As noted, level of detail probably requires complementary data to space-based measurements, the latter of which are more suited to characterizing emissions and transport rather than detailed characteristics of the aerosols
	C-5c. Quantify the effect that aerosol has on cloud formation, cloud height, and cloud properties (reflectivity, lifetime,	Very Important	CLOUDS: (1) cloud cover, optical depth, reflectivity, (2) vertical and horizontal distribution (plus cloud overlap plus morphology including	See Objective C-2h	Nadir and multiangular radiometers (MODIS, MISR); lidars (CALIPSO, HSRL); microwave brightness temperatures; shortwave reflectances in	POR-1, 2, 4, 10, 12, 14, 20, 23, 24, 25	TO-1, TO-5, TO-14

Page 605 Cite Bookmark

Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
	cloud phase), including semi-direct effects.		organization and convective/stratiform character), (3) colocation with precipitation, aerosls, aerosol sources, vertical velocity, (4) condensate state, number, phase, (5) within cloud variability.		the near IR and visible bands; stereo photogrammetric methods that builds on and advances measurements pioneered by the MISR instrument on the Terra satellite.
	C-5d. Quantify the effect of aerosol-induced cloud changes on radiative fluxes (reduction in uncertainty by a factor of 2) and impact on climate (circulation, precipitation).	Important	Forcing and response: (1) radiative fluxes, (2) precipitation, (3) climate variables (winds, temperature, etc.).	See Objective C-2h	Nadir and multi angular radiometers (MODIS, MISR); Lidars (CALIPSO, HSRL); microwave brightness temperatures; shortwave reflectances in the near IR and visible bands; stereo photogrammetric methods that builds on and advances measurements pioneered by the MISR instrument on the Terra satellite.	POR-1, 23, 5, 6, 7, 10, 20, 23, 24, 25, 28, 31	TO-1, TO-5, TO-14
QUESTION C-6. Seasonal to Decadal Predictions, Including Changes and Extremes (C-6 and C-7). Can we significantly improve seasonal to decadal forecasts of societally relevant climate variables? [see footnote 1]	C-6a. Decrease uncertainty, by a factor of 2, in quantification of surface and subsurface ocean states for initialization of seasonal-to-decadal forecasts.	Very Important	Sea-surface height	Spatial: 1-3 km; Temporal: approximately weekly	3 nadir-looking altimeters working together (e.g., SWOT)	POR-27
			Sea-surface salinity	Spatial: 5-10 km; Temporal: 2-3 days; Uncertainty 0.1-0.2 psu	Aquarius-like (SMOS, SMAP)	POR-23
			Sea-ice thickness	Freeboard height (from which thickness is derived); <3 cm uncertainty; Spatial: few km; Temporal: 10 days	Altimetry (e.g., ICESat-2, CryoSat-2)	POR-13, 14, 27, 29
			Sea-ice fraction	Spatial: 1 km; Temporal: daily	Microwave imagers (e.g., AMSR)	POR-1, 23	TO-11
			Sea-surface temperature	Spatial: 1-3 km; Temporal: resolved diurnal cycle	Microwave, IR imagers	POR-1, 9, 10, 24
			Surface vector winds	Spatial: few km; Temporal: daily	Scatterometer (e.g., QuikSCAT)	POR-23, 28	TO-11 (if scatterometer and tuned to stress)
			Subsurface temperatures	Spatial: 1 km horizontial, 1 m vertical; Temporal: daily; Accuracy: 0.07°C	Lidar
			Surface currents	Spatial: 5-10 km, wide swath; Temporal: 1-2/day; Random errors ≤1 m/s	Doppler scatterometer		TO-11
			Ocean mass	Spatial:100 km; Accuracy: 2 cm	Gravity (e.g., GRACE-FO)	POR-30
	C-6b. Decrease uncertainty, by a factor of 2, in quantification of land surface states for initialization of seasonal forecasts.	Important	Soil moisture	Daily at 10 km, to within 0.04 volumetric percent	L-band radar and radiometer (e.g., SMAP)	POR-12, 23
			Freeze-thaw state	Weekly at 10 km	Passive microwave radiometers, scatterometers, SAR	POR-12, 23
			Total water storage	Weekly at 100 km, to within 0.04 volumetric percent on average	Gravity (e.g., GRACE-FO)	POR-30
			Vegetation phenology (FPAR)	Weekly at 10 km, to within 0.05	MODIS, AVHRR-like vegetation measurements	POR-9, 21, 24
			Snow water equivalent	Daily at 10 km, to within 1 cm SWE	Combination of sensors, e.g., later altimetry, polarimetric imaging radar, microwave imaging radar, radiometers	POR-1, 9, 12, 14, 23, 24, 25, 28
	C-6c. Decrease uncertainty, by a factor of 2, in quantification of stratospheric states for initialization of seasonal-to-decadal forecasts.	Important	Polar vortex winds	Spatial: 5 degrees latitude/longitude; Temporal: daily	Radiometers and limb-sensing instrument for vertical resolution (infer observable using geostrophic approximation)	POR-16, 17, 18
*QUESTION C-7.* How are decadal-scale global atmospheric and ocean circulation patterns changing, and what are the effects of	C-7a. Quantify the changes in the atmospheric and oceanic circulation patterns, reducing the uncertainty by a factor of 2, with desired confidence levels	Very Important	COMMON TO ALL C-7: Observables to characterize the modes of circulation and trends in the global dynamical, thermodynamical, and water	COMMON TO ALL C-7: Sampling that allows the resolution of processes on spatial scales better than 0.5 degrees latitude‐longitude. This would also	COMMON TO ALL C-7: Nadir-viewing and limb soundings in the visible, infrared, microwave. Lidar-in-space. Wind profiler. Aerosols, water	POR-1, 3, 4, 5, 9, 11, 12, 16, 21, 23, 24, 25, 26, 27, 28, 31	TO-1, 2, 4, 5, 9, 11, 12, 13, 15, 16, 17, 18, 20, 21

Page 606 Cite Bookmark

Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
these changes on seasonal climate processes, extreme events, and longer term environmental change?	of 67% (likely in IPCC parlance).		systems: land and ocean surface temperature, vertical profile of atmospheric temperature and moisture, clouds, 3D wind profiles, surface to 5 km depth ocean temperature, salinity and currents. For ENSO and interannual time scales: SST, subsurface ocean properties, tropical winds. For AMOC, and decadal time scales in particular: SST and salinity to infer water density and ocean currents to determin stream functions. For changes in the position and intensity of the jets: (1) vertically resolved temperature in the UT/LS, to specify tropopause height, (2) precipitation at surface, as confirmation of Hadley cell location, (3) O₃ and H₂O in the UT/LS with higher vertical resolution, to enable definition of chemical tropopause, (4) vertical distribution of stratospheric and tropospheric aerosols. For regional climate quanitification: observations of tracer transport (e.g., aerosols), moisture and cloud properties. SST, SSS, SSH, subsurface ocean temperatures and salinity; sea-ice extent, thickness, thermodynamic state, and albedo.	enable comparisons of the simulation fidelity between increasing high-resolution (better than 0.5 degrees latitude‐longitude) models over the next decade and the observations. Measurement Requirements: Vertical Resolution and Range: ~1 km. (surface to lower stratosphere). Measurement Requirements. Horizontal resolution/range: 1/2° latitude × 1/2° longitude / Global; Temporal Sampling: minimum daily; Precision: 20%; Sufficient accuracy to address the regional variability and detection-attribution of forced climate change at the 67% confidence level or better, and to be used in conjunction with model simulations and reanalyses.	vapor, cloud, and sea-ice remote sensing.
	C-7b. Quantify the linkage between natural (e.g., volcanic) and anthropogenic (greenhouse gases, aerosols, land-use) forcings and oscillations in the climate system (e.g., MJO, NAO, ENSO, QBO). Reduce the uncertainty by a factor of 2. Confidence levels desired: 67%.	Important				POR-1, 2, 3, 4, 5, 11, 15, 16, 17, 22, 24, 31	TO-1, 2, 3, 4, 5, 6, 9, 11, 12, 13, 14, 15, 16, 17, 18, 20
	C-7c. Quantify the linkage between global climate sensitivity and circulation change on regional scales including the occurrence of extremes and abrupt changes. Quantify the expansion of the Hadley cell to within 0.5 degrees latitude per decade (67% confidence desired); changes in the strength of AMOC to within 5% per decade (67% confidence desired); changes in ENSO spatial patterns, amplitude, and phase (67% confidence desired).	Very Important				POR-1, 3, 4, 12, 23, 24, 25, 26, 28, 31	TO-1, 4, 5, 13, 14
	C-7d. Quantify the linkage between the dynamical and thermodynamic state of the ocean upon atmospheric weather patterns on decadal time scales. Reduce the uncertainty by a factor of 2 (relative to decadal prediction uncertainty in IPCC, 2013). Confidence level: 67% (likely).	Important				POR-1, 3, 4, 12, 21, 25, 26, 27, 28, 29	TO-1, 4, 5, 11, 13, 15, 20
	C-7e. Provide observational verification of models used for climate projections. Are the models simulating the observed evolution of the large-scale patterns in the atmosphere and ocean circulation, such as the frequency and magnitude of ENSO events, strength of AMOC, and the poleward expansion of the subtropical jet (to a 67% level correspondence with the observational data).	Important				POR-1, 3, 4, 5, 11, 12, 16, 17, 21, 23, 24, 25, 26, 28, 31	TO-1, 4, 5, 6, 9, 11, 12, 13, 15, 16, 17, 18, 20

Page 607 Cite Bookmark

Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
QUESTION C-8. Causes and Effects of Polar Amplification. What will be the consequences of amplified climate change already observed in the Arctic and projected for Antarctica on global trends of sea-level rise, atmospheric circulation, extreme weather events, global ocean circulation, and carbon fluxes?	C-8a. Improve our understanding of the drivers behind polar amplification by quantifying the relative impact of snow/ice-albedo feedback versus changes in atmospheric and oceanic circulation, water vapor, and lapse rate feedback.	Very Important	Sea-ice concentration/extent/type	Daily at 10 km resolution	Continuity of multichannel passive microwave (e.g., SSMI, SSMIS), sea-ice classification with dual pol SAR (e.g., ENVISAT, Radarsat) or scatterometers.		TO-11, 15, 17
			Sea-ice thickness	Daily at 1 km resolution	Laser and radar altimetry (e.g., ICESat2, CryoSat)
			Atmospheric boundary layer (surface temperature profiles, surface-air fluxes, water vapor, clouds).	Daily at 25 km spatial resolution, 200 m vertical resolution in the planetary boundary layer	Sounders and imagers at high horizontal resolution
			Atmospheric soundings (tropopause and lower stratosphere)
			Snow cover extent	Daily at 10 km resolution	Continuity of multichannel passive microwave (e.g., SSMI, SSMIS)
	C-8b. Improve understanding of high-latitude variability and midlatitude weather linkages (impact on midlatitude extreme weather and changes in storm tracks from increased polar temperatures, loss of ice and snow cover extent, and changes in sea level from increased melting of ice sheets and glaciers).	Very Important	Sea-ice concentration/extent/type	Daily at 10 km resolution, within 5%	See Objective C-8a
			Sea-ice thickness	Daily at 1 km resolution, within 20 cm	See Objective C-8a
			Atmospheric boundary layer (surface temperature profiles, surface-air fluxes, water vapor, clouds).	Daily at 25 km spatial resolution, 200 m vertical resolution in the planetary boundary layer	See Objective C-8a
			Atmospheric soundings (tropopause and lower stratosphere)		See Objective C-8a
			Snow cover extent	Daily at 10 km resolution	See Objective C-8a
			Sea-surface temperatures	Daily at a few kilometers, within 0.1 K	Microwave, IR instr (e.g., VIIRS, MODIS)
			Snow depth on land and sea ice	Daily at 1 km, within 10 km, within 20cm	Collocated Ku/Ka-band radar altimeter
			Snow water equivalent	Daily at 10 km, to within 1 cm SWE	Combination of sensors (e.g., laser altimetry, polarimetric imaging radar, microwave imaging radar, radiometers)
	C-8c. Improve regional-scale seasonal to decadal predictability of Arctic and Antarctic sea-ice cover, including sea-ice fraction (within 5%), ice thickness (within 20 cm), location of the ice edge (within 1 km), timing of ice retreat and ice advance (within 5 days).	Very Important	Sea-ice concentration/extent/type	Daily at 10 km resolution within 5%	See Objective C-8a
			Sea-ice thickness	Daily at 1 km resolution, within 20 cm	See Objective C-8a
			Snow on sea ice	Daily at 100 m resolution, within 5 cm	Collocated Ku/Ka-band radar altimeter, IceBridge
			Sea-ice motion and deformation	3‐day and weekly, 10 km resolution within 10 km	Continuity of multichannel passive microwave (e.g., SSMI, SSMIS)
			Melt pond fraction	Daily, 1 km resolution	Visible imagery (e.g., MODIS, VIIRS)
			Sea-surface temperatures	Daily at a few kilometers, within 0.1 K	Microwave, IR instr (e.g., VIIRS, MODIS)
			Snow cover extent	Daily at 10 km resolution, within 10 km	See Objective C-8a
			Atmospheric boundary layer (surface temperature profiles, surface-air fluxes, water vapor, clouds).	Daily at 25 km spatial resolution, 200 m vertical resolution in the planetary boundary layer	See Objective C-8a
	C-8d. Determine the changes in Southern Ocean carbon uptake due to climate change and associated atmosphere/ocean circulations.	Very Important	Atmospheric pCO2 (i.e., within the atmospheric boundary layer)	Monthly at 100 km by 100 km spatial scales. Air-sea pCO₂ difference accurate to ±3 to 15 μatm, implying no more than ±2 to 10 μatm uncertainty in atmospheric pCO2. Aim for 25% total flux uncertainty.	Schimel el al. RFI#2 submission: high-resolution spectroscopic observations of reflected sunlight in near infrared CO₂ and CH₄, such as provided by OCO-2. Possibility of retrieving full flux from atmospheric inversion will require multiple satellites.

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
				Further modeling and OSSE work will help to confirm requirements.	Kawa et al. RFI#2: lidar retrieval (e.g., ASCENDS) Singh et al. RFI#2: 2-μm lidar (e.g., IPDA lidar) Regression methods: use altimetery for sea-surface height, ocean color for biological productivity/upper ocean upwelling
			Upper ocean pCO2 (i.e., within the mixed layer)	Monthly at 100 km by 100 km spatial scales	Mannino et al RFI#2: ocean color (e.g., GEO-CAPE: high-temporal measurements of top of the atmosphere radiances from 350-900 nm (minimum of 25 bands; SNR > 1000) plus 1240 nm (SNR > 250) and 1640 nm (SNR > 180) with ~1000 biogeochemical Argo floats profiling every 10 days to provide upper in situ measurements
			Surface wind speed	Surface wind: monthly means at 100 km resolution; would prefer daily at oceanic eddy-resolving resolution	Wind: scatterometer preferred, passive microwave wind speed possible		TO-11 (if scatterometer and tuned to stress)
			SST or mixed-layer temperature	SST: monthly means at 100 km resolution; would prefer daily at eddy-resolving resolution to minimize or study eddy impacts	SST: microwave SST (microwave needed because of persistent cloud cover in region)
	C-8e. Determine how changes in atmospheric circulation, turbulent heat fluxes, sea-ice cover, fresh water input, and ocean general circulation affect bottom water formation.	Important	Atmospheric boundary layer temperature	Temperature at 2 m elevation to 0.2°C, and surface-specific humidity, both at spatial scale of oceanic eddies	Humidity inferred from brightness temperature (e.g., SSM/I). Temperature inferred fromreanalysis or infrared or microwave atmospheric profiler (e.g., AIRS or AMSU) with near surface measurement capability.
			Surface wind speed	Surface wind: monthly means at 100 km resolution; would prefer daily at oceanic eddy-resolving resolution	Wind: scatterometer preferred, passive microwave wind speed possible
			Surface temperature, salinity, density SST, or mixed layer temperature surface salinity (not easy from space at cold temperatures) or melt water input?	SST and SSS: 2-5 day sampling intervals, at eddy scales. Goal to obtain density to 0.03 kg/m³ or temperature to 0.2°C, consistent with threshold criteria used for mixed-layer depth definition. Freshwater input/ice melt could also be helpful on monthly time scales.	SST: microwave SST (microwave needed because of persistent cloud cover at high latitudes) SSS: surface salinity desirable. Very difficult observation at cold temperatures. Use Argo profiling floats and climatology if satellite retrievals not feasible. Freshwater input, ice melt: GRACE, sea-ice extent, ice thickness
	C-8f. Determine how permafrost-thaw-driven land cover changes affect turbulent heat fluxes, above and belowground carbon pools, and resulting greenhouse gas fluxes (carbon dioxide, methane) in	Important	Freeze-thaw state	Weekly, at 100 m horizontal and 5-10 cm vertical resolution	Passive microwave radiometers, scatterometers, SAR; InSAR, C- and L-band SAR; Tomographic SAR; Airborne EM; GPR; SMAP	POR-12(PALSAR) POR-12(Sentinel-1) POR-23 (SMAP)	TO-17
			Active layer thickness	Biweekly (except in winter, when no measurement is needed) at 100 m horizontal and 5 cm vertical resolution	AirMOSS (P-band SAR); UAVSAR (L-band InSAR); Airborne-EM; OIB low-frequency radars; ground based (or airborne) GPR	POR-12 (L-band PALSAR POR-12 (NISAR)

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
	the Arctic, as well as their impact on Arctic amplification.		Lake and wetland fraction	Bimonthly at 100-250 m	Optical instruments (e.g., MODIS, Landsat, SPOT, Sentinel-2), active SAR instruments (C and L bands)	POR-12(PALSAR) POR-12(Sentinel-1) POR-9 (Landsat) POR-9 (Sentinel-2) POR-27 (SWOT) POR-21 (MODIS)	TO-18
			Snow water equivalent	Daily at 1 km, within 1 cm SWE	Combination of sensors: e.g., laser altimetry, polarimetric imaging radar, microwave imaging radar, radiometers	POR-23 (AMSR-2) POR-23 (SMOS)	TO-16
			Snow cover extent	Daily at 1 km resolution, within 2 days uncertainty	Need for continuity of multichannel passive microwave; optical and infrared instruments (e.g., MODIS)	POR-24 (VIIRS) POR-9 (Landsat) POR-9 (Sentinel-2) POR-21 (MODIS)	TO-18
			Surface elevation	Annually at 50 m resolution, within 2 cm uncertainty	Active SAR instruments (Interferometry), Lidar; US L-band SAR; DLR Tandem-X and Tandem-L; ICESat-ATLAS	POR-12 (L-band PALSAR) POR-12 (S-band NISAR) POR-12(C-band Sentinel-1) POR-14 (ICESat-ATLAS)	TO-19, 20
			Permafrost thickness and 3D geometry	Once every 10 years, with 100 m horizontal resolution	Tomographic SAR; Satellite-based EM; GPR; P-band SAR; OIB VHF and UHF radars	POR-12 (P-band SAR)
			Land surface temperature (LST)	Daily, with 1 km resolution and 1 K precision	MODIS, AVHRR, Sentinel	POR-24 (VIIRS)? POR-25 (Landsat) POR-25 (NISAR TIS) POR-22 (Sentinel-3) POR-21 (MODIS)	TO-18
			Land cover state and change	Monthly, with 30 m resolution	Landsat, SPOT, Sentinel-2, HyspIRI	POR-9 (Landsat) POR-9 (Sentinel-2)	TO-18
			Permafrost methane feedback (seep flux from thaw lakes)	Weekly during lake freeze-up season (Oct-Dec), ideally at 5-10 m, acceptable 30 m resolution	Quadpole L-band SAR (e.g., PALSAR)	POR-12(L-band PALSAR)
	C-8g. Determine the amount of pollutants (e.g., black carbon, soot from fires, and other aerosols and dust) transported into polar regions and their impacts on snow and ice melt.	Important	Aerosol optical depth	See requirements for AEROSOLS in C-2h, C-5a, and requirements for particulate matter (PM) in W-1a, W-5a, W-6a	Nadir viewing Radiometers (e.g., MODIS); Multiangle viewing radiometers (MISR); Current technology lidar (CALIPSO); More modern technology lidar (HSRL); HSRL can be used for vertically resolved profiles that better enable (1) distinguishing aerosols and clouds, (2) increased sensitivity (detecting lower concentrations of aerosol), (3) better resolution of aerosol amounts nearer the surface (lower altitude), and (4) more accurate aerosol optical depths. Multiangle, multispectral polarimeters can provide improved column integrated information on aerosol composition such as refractive index (including absorption), particle size, and variance. The combination of HSRL and a multiangle, multispectral polarimeter has improved accuracy beyond each individual instrument.
			Aerosol absorption optical depth	See requirements for AEROSOLS in C-2h, C-5a

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO

			Snow depth, cover, albedo on land, glaciers and sea ice	See requirements for H-1c
			From C-2h: Meteorological properties in vicinity of aerosols and clouds (temperature, winds, humidity) to characterize the environment in which the cloud is forming.	See requirements for C-2h	See C-12. IR sounders (e.g., CrIS, IASI) plus CLARREO-like intercalibration, GNSS-RO for zonal temperature trend in 5-20 km altitude
	C-8h. Quantify high-latitude low cloud representation, feedbacks, and linkages to global radiation.	Important	Cloud properties (cloud fraction, cloud vertical distribution, cloud liquid water content, cloud ice water content, droplet effective radius, ice particle effective diameter, number concentration, in-cloud circulations, cloud top turbulence/entrainment, vertical velocity and cloud phase)	Cloud Fraction (%) <1%; Cloud Liquid Water Content +20%; Cloud Ice Water content +20%; Cloud top and base height <75 m	Continuity of lidar/radar instruments with need for more complete sampling and vertical resolution, synergistic passive-active instruments
			Radiation (surface upwelling and downwelling flux for longwave and shortwave; TOA fluxes), Turbulent radiative fluxes	Daily, within 5 W/m² for radiative fluxes, within 5‐10 W/m² for turbulent fluxes	Continuity of TOA radiative fluxes from CERES and MODIS/VIIRS
			Atmospheric temperature and humidity		Need for collocated and finer spatial and vertical resolution boundary layer temperature and humidity
			Aerosol concentration and composition		Continued polar lidar needed (e.g., CALIOP), advanced lidar techniques like HSRL
			Sea-ice fraction	Daily, 10 km resolution, accuracy of 5%
			Sea-ice thickness	Daily at 1 km resolution, accuracy of 20 cm
	C-8i. Quantify how increased fetch, sea-level rise and permafrost thaw increase vulnerability of coastal communities to increased coastal inundation and erosion as winds and storms intensify.	Important	Wave heights	(Hs, significant wave height) 25 km spatial resolution; 3 hr revisit; 0.5 m uncertainty	Radar altimeter (e.g., Jason-3) for significant wave height
			Fetch/ice edge	Daily, at 10 km resolution, within 5 km	Passive and active microwave
			Winds	(U10, windspeed) 10 km spatial resolution; 3 hr revisit; 2 m/s uncertainty	Scatterometer, passive microwave, SAR		TO-11 (if scatterometer and tuned to stress)
			Ocean currents	Spatial: 5‐10 km, wide swath, random errors ≤1 m/s	Radar altimeter (e.g., Jason-3) for surface currents, Doppler scatterometer
QUESTION C-9. Ozone and Other Trace Gases in the Stratosphere and Troposphere. How are the abundances of ozone and other trace gases in the stratosphere and troposphere changing, and what are the implications for Earth’s climate?	C-9a. Quantify the amount of UV-B reaching the surface, and relate to changes in stratospheric ozone and atmospheric aerosols.	Important	Surface UVB	Global 5º latitude/10º longitude, surface only, weekly sampling, precision 5%		GOME-2; Suborbital: Baseline Surface Radiation Network (BSRN)	TROPOMI
		Important	Total column ozone	Global 1º latitude/2º longitude, surface only, weekly sampling for column, surface through stratosphere, precision 3 Dobson Units		POR-9, 11 SBUV-2, OMI, OMPS, GOME-2; Suborbital: Network for the Detection of Atmospheric Composition Change, Global Climate Observing System Reference Upper-Air Network (GRUAN), Southern Hemisphere Additional Ozonesondes	TROPOMI

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			Vertical profiles of temperature in UTS (upper troposphere and stratosphere), for quantifying radiative forcing	Vertical resolution and range: <1 km in UTLS, <3 km in mid-upper stratosphere; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: weekly; Precision: 1-2 K.	UV, visible, and infrared solar, lunar, and stellar occultation (e.g., ACE-FTS, GOMOS, HALOE, POAM, SAGE) High precision, high vertical resolution (<1 km), climate (trend) quality, but poor spatial coverage unless a constellation is used. Infrared and microwave limb emission (e.g., HIRDLS, MIPAS, MLS, Odin SMR)Many species, 3-4 km vertical resolution, night and day, global coverage Visible limb scattering (e.g., SME, OMPS-LP, OSIRIS). Lidar (e.g., CALIPSO-CALIOP). High (meters) vertical resolution. Radar (e.g., CloudSat CPR). Nadir-viewing solar reflection/scattering (e.g., AIM-CIPS, MODIS, OCO-2). Good (km) horizontal resolution Suborbital: Ground-based and balloon/aircraft measurements of ozone and ozone depleting substances to support emissions estimation and trend determination	POR-6, 16, 17, 18ACE-FTS (not global), Auro MLS (not 1 km verical resolution; not self-calibrating), GPS-RO (extreme path length), MSU/SSU/AMSU (10 km vertical resolution; not self-calibrating); Suborbital: Global Climate Observing System Reference Upper-Air Network (GRUAN), NWS Upper-air Observations Program	TO-13
			Vertical profiles of radiatively active gas concentrations in the UTS, for quantifying radiative forcing	Concentration of O3: Vertical resolution and range: <1 km in UTLS, <3 km in mid-upper stratosphere; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: weekly; Precision: 10%. Concentration of H2O: Vertical resolution and range: <1 km in UTLS, <3 km in mid-upper stratosphere; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: weekly; Precision: 10%.		POR-6, 16, 17, 18 ACE-FTS (not global; not 1 km vertical resolution), Aura MLS (not 1 km vertical resolution; not self-calibrating), OMPS-L (not 1 km vertical resolution; not self-calibrating (?)); Suborbital measurements: Network for the Detection of Atmospheric Composition Change, Global Climate Observing System Reference Upper-Air Network (GRUAN), Southern Hemisphere Additional Ozonesondes (SHADOZ) SAGE III (ISS) (not global; 18 Feb 2017 launch)	TO-12
			Vertical profiles of UTS aerosol radiative properties, for quantifying radiative forcing	Vertical resolution and range: <1 km in UTLS; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: weekly; Precision: 30%.		POR-2, 16, 18 ACE-FTS [not global; not 1 km vertical resolution], Odin OSIRIS [not 1 km vertical resolution; not polar night; no particle size info], CALIPSO CALIOP [near end-of-life] SAGE III (ISS) [not global]	TO-1, 2
			Volcanic and biomass burning emissions, for process studies (sources and transport)	Volcanic Aerosol: Vertical resolution and range: <1 km in UTLS; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: daily during events; Precision: 30%. Concentrations of gases from volcanic emissions: Vertical resolution and range: <1 km in UTLS; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: daily during events; Precision: ~20%, but species dependent.		POR-2, 16, 17, 18 Volcanic Aerosol: CALIPSO CALIOP [near end-of-life] Concentrations of gases from volcanic emissions: ACE-FTS [not global; not 1 km vertical resolution], MLS [not 1 km vertical resolution; not NO₂] SAGE III (ISS) [not enough sampling to track the sources]	TO-1, 2, 12

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

CLIMATE VARIABILITY AND CHANGE PANEL
SCIENCE			MEASUREMENT
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			Deep convective clouds, for process studies (sources)	Vertical resolution and range: <1 km in UTLS; Horizontal range: Global; Horizontal and temporal sampling: event-specific, episodic; Precision: 30%.		POR-1, 4, 10, 17, 21, 23 Aura MLS (not 1 km vertical resolution), Aqua AIRS, Aqua AMSR-E, Aqua MODIS, CloudSat	TO-5
			Small-scale transport and the Brewer-Dobson circulation, for process studies (transport)	Vertical resolution and range: <1 km in UTLS, <3 km in mid-upper stratosphere; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: event-driven for small scale, weekly for BD; Precision: 30%.		POR-16, 17 ACE-FTS [not global; not 1 km vertical resolution], Aura MLS [not 1 km vertical resolution]	TO-12, 13
			Dynamical features such as the polar vortex, for process studies (transport)	Vertical resolution and range: <1 km in UTLS, <3 km in mid-upper stratosphere; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: daily to weekly; Precision: 1-2 K (T), 30% (UV).		POR-6, 16, 17, 18 ACE-FTS [not global; not 1 km vertical resolution], Aura MLS [not 1 km vertical resolution], GPS-RO [extreme path length]	TO-12, 13
			Planetary and gravity waves, for process studies (transport)	Vertical resolution and range: <1 km from cloud top to stratopause; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: daily to weekly; Precision: 1-2 K (T).		POR-6, 16, 17, 18 ACE-FTS [not global; not 1 km vertical resolution], Aura MLS [not 1 km vertical resolution], GPS-RO [extreme path length]	TO-12, 13
			Stratospheric ozone and related constituents, for process studies (chemistry)	Vertical resolution and range: <1 km from cloud top to stratopause; Horizontal resolution/range: 5° latitude × 10° longitude / Global; Temporal sampling: daily to weekly; Precision: 5% (O₃), 10% (others).		POR-16, 17, 18 ACE-FTS [not global; not 1 km vertical resolution], Aura MLS [not 1 km vertical resolution; only some of the constituents]; Suborbital measurements: Network for the Detection of Atmospheric Composition Change, Global Climate Observing System Reference Upper-Air Network (GRUAN), Southern Hemisphere ADditional OZonesondes (SHADOZ), Advanced Global Atmospheric Gases Experiment and NOAA Halocarbons and Other Trace Species Network SAGE III [not global; only some of the constituents]	TO-12

¹ As noted in the text, all of the indicated measurements for Questions C-6 and C-7 would be useful, but the absence or excessive coarseness of any of the measurements would not be a “deal-breaker.” This question is best considered not as a motivation for a mission but rather as a beneficiary of measurements taken to address other questions. Indicating here which measurements are already being taken is, in a way, extraneous.

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

EARTH SURFACE AND INTERIOR PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
*QUESTION S-1.* How can large-scale geological hazards be accurately forecast in a socially relevant time frame?	S-1a. Measure the pre-, syn-, and posteruption surface deformation and products of Earth’s entire active land volcano inventory at a time scale of days to weeks.	Most Important	Land-surface deformation	At least two components of land-surface deformation and strain localization (e.g., surface fracturing) over length scales ranging from 10 m to 1,000 km and a precision of 1 mm at a sampling frequency related to the volcanic activity. Regionally sampled global coverage.	L- or S-band InSAR with ionospheric correction, [GPS/GNSS]	POR-12 (NISAR)	TO-19
			Topography	High spatial resolution (5 m) bare-Earth topography at 1 m vertical accuracy over all volcanoes	Spacecraft swath-lidar or radar	POR-14 (ICESat-2)	TO-20
			Ground-surface composition and changes over time	Hyperspectral VNIR/SWIR (at the ~ 30 m spatial scale) and TIR data (at the ~ 60 m spatial scale) with 1-2 week revisit time, acquiring continuously for periods of weeks to months prior to an eruption to detect trends and change	High spatial-resolution imaging/spectometry—e.g., ASTER, Hyperion, HyspIRI (last decadal survey), Landsat (high spatial). OMI, AIRS (high temporal)	POR-9 (ASTER, OLI, ETM+), POR-21 (MODIS), POR-24 (VIIRS, SEVIRI)	TO-18
			Gas emissions, plume composition, particle size and temporal changes	Hyperspectral UV, NIR, SWIR, and TIR data (at ~1-10 km spatial scale) with daily revisit time. Multi- to hyperspectral VNIR/SWIR (at ~30 m) and TIR data (at ~60 m) with ~1 week revisit time. Acquiring continuously prior to and during eruptions to detect trends and measure eruptive emissions. Active (lidar and radar) and passive (MISR) data to characterize plume altitude	Global hyperspectral UV (e.g., OMI, OMPS) and TIR (e.g., AIRS, IASI) for SO₂, H₂S and ash; high-resolution NIR for CO₂ (e.g., OCO-2). High spatial-resolution (e.g., ASTER, HyspIRI) for small plumes. Space-borne lidar and radar (e.g., CALIPSO, CloudSat), multiangle visible-NIR imagers (e.g., MISR)	POR-9 (ASTER), POR-11 (OMPS, OMI), POR-20 (AIRS), POR-21 (MODIS)	TO-1, 2, 18
			Thermal output	Multispectral TIR data (including a 3-5 micron channel) at 100 m spatial resolution acquired at a temporal frequency of 1-24 hours to detect high-frequency changes in thermal output before and after an event	Moderate-resolution imaging/spectometry—e.g., ASTER, Landsat (high spatial) but at the high temporal scale of GOES, MODIS, AVHRR	POR-9 (ASTER), POR-21 (MODIS), POR-25 (ASTER, TIRS)	TO-18
	S-1b. Measure and forecast interseismic, preseismic, coseismic, and postseismic activity over tectonically active areas on time scales ranging from hours to decades.	Most Important	Land-surface deformation	At least two components of land-surface deformation 10 m to 1,000 km resolution and precision of 1-10 mm at a sampling frequency related to seismic/tectonic activity. Ideally, resolution of 1 mm/week. Need more than 10 years of observations to measure interseismic deformation	L- or S-band InSAR with ionospheric correction, [GPS/GNSS].	POR-12 (NISAR)	TO-19
			Large spatial scale gravity change	Gravity change for large events (GRACE and follow-on missions)	Gravity (e.g., GRACE-2)	POR-30 (GRACE-FO)	TO-9
			Reference frame	Stable terrestrial reference frame at 1 mm/yr accuracy	[VLBI, SLR, GPS/GNSS]	POR-7, 13 (Jason-3, LAGEOS)
			Topography	High spatial resolution (1 m), bare-Earth topography at 0.1 m vertical accuracy over selected tectonic areas	[aircraft/UAV lidar]	POR-14 (ICESat-2)	TO-20
			Land cover change	High spatial resolution (1 m) stereo optical imagery	{Commercial optical}	POR-9 (Pleiades)	COMMERCIAL
	S-1c. Forecast and monitor landslides, especially those near population centers.	Very Important	Land-surface deformation	At least two components of land-surface deformation at <50 m spatial resolution and 1 mm/yr at a temporal frequency <seasonal (InSAR and GPS/GNSS)	L- or S-band InSAR, [GPS/GNSS] {Complements ground-based seismic data}	POR-12 (NISAR)	TO-19
			High-resolution topography	Spatial resolution 1-5 m, vertical 0.5 m	[aircraft/UAV lidar]	POR-14 (ICESat-2)	TO-20
			Precipitation	Every 3 hours	Precipitation monitor (e.g., GPM)	POR-4 (GPM, CloudSat)	TO-5
			Permafrost melt	Radar, optical imaging, and InSAR	{Radarsat-2, commercial 1 m optical}	POR-12, 23 (RADARSAT-2, SMAP, SMOS)	TO-17

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

EARTH SURFACE AND INTERIOR PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			High spatial resolution time series of distribution of vegetation and rock/soil composition	Hyperspectral VNIR/SWIR and TIR data at 30-45 m spatial resolution and ~ weekly temporal resolution	Moderate-resolution imaging/spectometry—e.g., ASTER, Landsat, Hyperion but at slightly improved spatial resolution and much improved temporal resolution	POR-9 (ASTER, Landsat, Hyperion, Sentinel-2)	TO-18
	S-1d. Forecast, model, and measure tsunami generation, propagation, and run-up for major seafloor events.	Important	Topography and shallow bathymetry	High spatial resolution (1 m), bare-Earth topography at 0.1 m vertical accuracy over selected tectonic areas	[aircraft/UAV lidar]	POR-14 (ICESat-2)	TO-20
			Sea-surface tsunami waves	Wave height (0.1 m), period (seconds, minutes?)	Swath altimetry—e.g., SWOT {GPS/GNSS buoys, ocean altimetry, complements seafloor pressure changes}	POR-7, 27 (SWOT)	TO-21
			Ionospheric waves	Ionospheric imaging at 10 km spatial resolution and 10 minute sampling from GPS/GNSS arrays	Radio occultation—e.g., GPS/GNSS, COSMIC	POR-6, 7 (COSMIC)
			Global bathymetry and seamless nearshore bathymetry	Global marine gravity from swath radar altimetry (SWOT)	Swath altimetry	POR-27 (SWOT)	TO-21
			Optical, radar, and InSAR change detection on demand with low-latency processing and distribution	Enable high spatial resolution spaceborne or aircraft asset that can provide timely information to relief efforts	{Commercial 1 m optical, GPS/GNSS}	POR-9 (Pleiades, RADARSAT2)	COMMERCIAL
			Rapid characterization of the magnitude of earthquakes	1 Hz deformation time series	{Terrestrial seismic and GPS/GNSS networks}	POR-7, 13 (GNSS, GRACE-FO, Jason-3, LAGEOS, GRASP)	TERRESTRIAL
			All high-resolution visible to thermal IR imagery	Provide rapid acquisitions at the hours to 1-day time frame using either a constellation of small-sats and/or interconnectivity to other orbital assets in a sensor-web approach	Create new small-sat constellations to complement ground-based seismic, gas, thermal, scanning lidar monitoring systems. Expand on current orbital sensor webs such as ACE and the ASTER Urgent Request Protocol. NOTES: This is likely a NASA-specific focus, but could be partially satisfied with commercial participation.	POR-9 (Pleiades, Sentinel-2)	COMMERCIAL
*QUESTION S-2.* How do geological disasters directly impact the Earth system and society following an event?	S-2a. Rapidly capture the transient processes following disasters for improved predictive modeling as well as response and mitigation through optimal retasking and analysis of space data.	Most Important	All high-resolution visible to thermal IR imagery	Provide rapid acquisitions at the hours to 1-day time frame using either a constellation of small-sats and/or interconnectivity to other orbital assets in a sensor-web approach	Create new small-sat constellations to complement ground-based seismic, gas, thermal, scanning lidar monitoring systems. Expand on current orbital sensor webs such as ACE and the ASTER Urgent Request Protocol. NOTES: This is likely a NASA-specific focus, but could be partially satisfied with commercial participation.	POR-9 (Pleiades, Sentinel-2)	COMMERCIAL
		Most Important	Provide rapid deformation map acquisitions and interconnectivity to other sensors	At least two components of land-surface deformation over 10 m to 1000 km length scales at 10 mm precision and ASAP after the event. Adequate resolution of 1 cm/week for afterslip applications	InSAR	POR-12 (NISAR)	TO-19
	S-2b. Assess surface deformation (<10 mm), extent of surface change (<100 m spatial resolution) and atmospheric contamination, and	Very Important	Land-surface deformation	At least two components of land-surface deformation and surface fracturing over length scales ranging from 10 m to 1,000 km and temporal resolution of 1 mm/yr at a sampling frequency related to the volcanic	L- or S-band InSAR with ionospheric correction, [GPS/GNSS]	POR-12 (NISAR)	TO-19

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Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

EARTH SURFACE AND INTERIOR PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
	the composition and temperature of volcanic products following a volcanic eruption (hourly to daily temporal sampling).			activity (InSAR and GPS/GNSS) everywhere.
			Volume, composition, and temperature of all eruptive products and their changes over time	Hyperspectral VNIR/SWIR and TIR data at 30-45 m spatial resolution and ~ weekly temporal resolution, SAR backscatter data	Moderate-resolution imaging/spectometry—ASTER, Landsat, high-repeat time airborne/UAV data	POR-9 (ASTER), POR-21 (MODIS), POR-25 (ASTER, TIRS)	TO-18
			Mass and energy fluxes across solid Earth/atmospheric boundary	Hyperspectral VNIR/SWIR and TIR data at 30-45 m spatial resolution and ~ weekly temporal resolution, High-rate SNR GPS/GNSS data	Moderate-resolution imaging/spectometry—ASTER, Landsat, high-repeat time airborne/UAV data	POR-9 (ASTER), POR-21 (MODIS), POR-25 (ASTER, TIRS)	TO-18
			[Geospatial and numerical model development of future/continued hazard potential]	Hyperspectral VNIR/SWIR and TIR data at 30-45 m spatial resolution and ~ weekly temporal resolution. SAR backscatter data at >30 m (or better spatial resolution). Bare-Earth topography. High-rate SNR GPS/GNSS data. Synergy to past/future Landsat-style systems. Expanded GIS and integration with current databases.	Moderate-resolution imaging/spectometry—e.g., ASTER, Landsat, high-repeat time airborne/UAV data, [current plume dispersion, lahar and lava flow modeling]	POR-9 (ASTER), POR-21 (MODIS), POR-25 (ASTER, TIRS)	TO-18
	S-2c. Assess co- and postseismic ground deformation (spatial resolution of 100 m and an accuracy of 10 mm) and damage to infrastructure following an earthquake.	Very Important	Land-surface deformation	At least two components of land-surface deformation at 100 m spatial resolution and 1 mm/yr at a temporal frequency related to the tectonic activity (InSAR and GPS/GNSS). Need more than 10 years of interseismic observations and 5 years of post seismic observations	L- or S-band InSAR with ionospheric correction, [GPS/GNSS]	POR-12 (NISAR)	TO-19
			Large spatial scale gravity change	Gravity change for large events	Gravity (e.g., GRACE-2)	POR-30 (GRACE-FO)	TO-9
			Reference frame	Stable terrestrial reference frame at 1 mm/yr accuracy	[VLBI, SLR, GNSS]	POR-7, 13 (GRACE-FO, Jason-3, LAGEOS)	TO-9
			Topography	High spatial resolution (1 m), bare-Earth topography at 0.1 m vertical accuracy over selected tectonic areas	[aircraft/UAV lidar]	POR-14 (ICESat-2)	TO-20
			Optical imaging	Map surface rupture, liquefaction features and damage at spatial scales better than 5 m.	{Worldview}, [aircraft/drone imaging]	POR-9 (Pleiades)	COMMERCIAL, AIRBORNE
*QUESTION S-3.* How will local sea-level change along coastlines around the world in the next decade to century?	S-3a. Quantify the rates of sea-level change and its driving processes at global, regional, and local scales, with uncertainty <0.1 mm/yr for global mean sea-level equivalent and <0.5 mm/yr sea-level equivalent at resolution of 10 km.	Most Important	Surface melt	Weekly during melt season, 1 m horizontal resolution	Imagery (e.g., Landsat, Aster, WorldView)	POR-9 (Pleiades)	TO-18
			Ice topography	Monthly or less, uncertainty <(10 cm for mean, 25 cm/yr for change) over areas of 100 km²	Satellite and suborbital lidar	POR-14 (ICESat-2)	TO-7
			Snow density	50 km resolution with accuracy of 2 cm RMS in terms of snow water equivalent (SWE), averaged monthly		POR-14 (ICESat-2), POR-26 (SWOT), POR-27 (CryoSat-2)	TO-16
			Gravity	Monthly, uncertainty 1 cm water-equivalent thickness at resolution of 200 km at equator	Gravity (e.g., GRACE-2)	POR-30 (GRACE-FO)	TO-9
			3D surface deformation vectors on ice sheets	Monthly, cm/yr accuracy, 100 m resolution and better than seasonal sampling	InSAR	POR-12 (NISAR)	TO-19
			Sea-surface height	Monthly, 2 cm height accuracy at 100 km resolution	Radar altimetry (e.g., Jason-3, Jason-CS, SWOT), [global tidal gauge network]	POR-26, 27 (Lason-3, SWOT)	TO-21
			Terrestrial reference frame	Stability at <0.1 mm/yr	Possible (e.g., GRASP), [maintain high quality of co-located sites (minimum of 8-10)]	POR-7, 13 (GRACE-FO, Jason-3, LAGEOS, GRASP)

Page 616 Cite Bookmark

Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

EARTH SURFACE AND INTERIOR PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			In situ temperature/salinity	Comparable to Argo at 300 km resolution or better	N/A
			Ice velocity	Monthly or less, uncertainty <10 cm/yr over areas of 100 km²	InSAR	POR-12 (NISAR)	TO-19
			High-resolution topography	Vertical accuracy of 10 cm, resolution 1 m		POR-14 (ICESat-2)	TO-20
	S-3b. Determine vertical motion of land along coastlines at uncertainty <1 mm/yr.	Most Important	Bare-earth topography	Global measurements made once to produce high-resolution (1-m horizontal, 10-cm vertical) bare-earth topographic model. Focused regional surveys at comparable resolution used to image landscape change from the globally established baseline.	[aircraft/UAV lidar, UAV SAR?]. NOTES: In cases where landscape changes are substantial and unobscured by vegetation, topographic models created from high-resolution stereo satellite imagery may supplement airborne lidar bare-earth elevation models.	POR-14 (ICESat-2)	TO-20
		Most Important	Land-surface deformation	5-10 mm vertical precision, <50 m horizontal, weekly	InSAR	POR-12 (NISAR)	TO-19
*QUESTION S-4.* What processes and interactions determine the rates of landscape change?	S-4a. Quantify global, decadal landscape change produced by abrupt events and by continuous reshaping of Earth’s surface from surface processes, tectonics, and societal activity.	Most Important	Bare-earth topography	Global measurements made once to produce high-resolution (1 m horizontal, 10 cm vertical) bare-earth topographic model. Focused regional surveys at comparable resolution used to image landscape change from the globally established baseline.	[aircraft/UAV lidar, UAV SAR?]. NOTES: In cases where landscape changes are substantial and unobscured by vegetation, topographic models created from high-resolution stereo satellite imagery may supplement airborne lidar bare-earth elevation models.	POR-14 (ICESat-2)	TO-20
			Land-surface deformation	5-10 mm vertical precision, <50 m horizontal, weekly	L- or S-band InSAR, [UAVSAR], [GNSS].	POR-12 (NISAR)	TO-19
			High spatial resolution time series of changes in optical surface characteristics	Optical ground characteristics at <1 m resolution with weekly repeat time	{Worldview-2 / 3 satellites}	POR-9 (Pleiades)	COMMERCIAL
			Measurement of rock-, soil-, water-, and ice-mass change	Satellite gravimetry	Gravity (e.g., GRACE-2)	POR-30 (GRACE-FO)	TO-9
			Measurement of rainfall and snowfall rates	Multiple times per day via satellite constellation	Like GPM	POR-4 (GPM, CloudSat)	TO-5
			Reflectance for freeze/thaw spatial and temporal distribution	<50 m horizontal, weekly	Radar reflectivity	POR-9 (Pleiades, RADARSAT2), POR-14 (NISAR	TO-19
	S4b. Quantify weather events, surface hydrology, and changes in ice/water content of near-surface materials that produce landscape change.	Important	Measurement of rainfall and snowfall rates	Multiple times per day via satellite constellation	Precipitation monitor (e.g., GPM)	POR-4 (GPM, CloudSat)	TO-5
			Reflectance for freeze/thaw spatial and temporal distribution	<50 m horizontal, weekly	Radar reflectivity	POR-12 (NISAR)	TO-19
			Optical characterization of spatial and temporal distribution of freeze/thaw	<1 m horizontal, weekly	{Worldview-2 / 3 satellites}	POR-9 (Pleiades)	COMMERCIAL
			Reflectance for snow depth/snow water equivalent	SWE at ~100 m resolution suitable for SWE values to 2.5 m.	Ka-band radar or laser altimeter (depth) and SAR (density)	POR-17 (KaRIn, SWOT)	TO-16, 19
			Reflectance for snow depth/snow water equivalent	SWE at ~100 m resolution suitable for SWE values to 2.5 m.	InSAR	POR-12 (NISAR)	TO-19
			Soil/root zone moisture content		Soil state/moisture (e.g., SMAP)	POR-12 (NISAR), POR-23 (SMAP)	TO-17
			Soil/root zone moisture content	Vadose zone soil moisture at <5 m horizontal resolution with daily repeat times	[AIRMOSS]		AIRCRAFT
	S4c. Quantify ecosystem response to and causes of landscape change.	Important	High spatial resolution time series of distribution of vegetation in VIS/NIR	NIR at <5 m with weekly to monthly repeat time	{Worldview-2 / 3 satellites}	POR-9 (ASTER), POR-21 (MODIS), POR-25 (ASTER, TIRS)	COMMERCIAL
			Observations of canopy structure and carbon inventory	1 m resolution canopy structure collected seasonally	[Aircraft/UAV waveform lidar]	POR-14 (ICESat-2)	TO-20

Page 617 Cite Bookmark

Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

EARTH SURFACE AND INTERIOR PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
				25 m resolution vertical structure observations collected seasonally and globally	GEDI	POR-14 (ICESat-2)	TO-20, 22
			Bare-earth topography	Global measurements made once to produce high-resolution (1 m horizontal, 10 cm vertical) bare-earth topographic model. Focused regional surveys at comparable resolution used to image landscape change from the globally established baseline.	[aircraft/UAV lidar, UAV SAR?]. NOTES: In cases where landscape changes are substantial and unobscured by vegetation, topographic models created from high-resolution stereo satellite imagery may supplement airborne lidar bare-earth elevation models	POR-14 (ICESat-2)	TO-20
			Observations of ecosystem status and near-surface material composition	Hyperspectral VNIR/SWIR and TIR data at 30-45 m spatial resolution and ~ weekly temporal resolution	Moderate-resolution imaging/spectometry—e.g., Landsat, ASTER, Hyperion, but with improved spectral and temporal resolution	POR-9 (ASTER, OLI, ETM+	) TO-18
*QUESTION S-5.* How does energy flow from the core to Earth’s surface?	S-5a. Determine the effects of convection within Earth’s interior, specifically the dynamics of Earth’s core and its changing magnetic field and the interaction between mantle convection and plate motions.	Very Important	Monitor secular variation in Earth’s magnetic field	LEO Multi-point simultaneous magnetic field vector measurements with global coverage, 0.1 nT/component precision, 1 nT/component absolute. Multi-year continuous observations.	Magnetometers (e.g., SWARM). NOTES: There are currently no suitable LEO vector magnetic satellite missions planned beyond Swarm.	POR-19 (SWARM)	TO-8
			Determine exchange of angular momentum between core and mantle from changes in earth rotation parameters	Observe changes in the Earth Orientation Parameters to 5 μs for the Length of Day and 50 μas for the corresponding xp, yp pole coordinates. Observe the nutation and precession of the Earth rotation axis to 0.0001″ for each component.	[VLBI]	POR-7, 13 (GRACE-FO, Jaso 3, LAGEOS, GRASP)	n- TO-9
			Map surface topography—moderate resolution	Measure topography to 5 m horizontal and 10 cm vertical resolution	{TerraSAR Tandem-X}		COMMERCIAL
			Map gravity field	Measure sea-surface height to 1 cm over 10 km distance	Radar altimetry (e.g., SWOT)	POR-26, 27 (SWOT)	TO-21
			Determine plate motions and deformation and track the evolution of plate boundaries	Continuous GPS/GNSS 1 mm/yr horizontal, 2 mm/yr vertical, <500 km sampling interval	[GNSS]	POR-7 (GNSS)
				SAR interferometry, 10 mm vertical, 100 mm horizontal	L-band InSAR with ionospheric correction	POR-12 (NISAR)	TO-19
				Marine or aeromagnetic high-resolution spatial magnetic anomalies, 10 nT, 1 km horizontal resolution	[aircraft magnetometer]		AIRCRAFT
				Sea floor geodesy, 5 mm/yr horizontal, 10 mm/yr vertical	[GPS acoustics]		GPS
				Improved reference frames through geodetic observations, 1 mm accuracy, 0.1 mm/yr stability horizontal and vertical	[VLBI, SLR, GNSS]	POR-7, 13 (GRACE-FO, Jaso 3, LAGEOS, GRASP)	n-
	S-5b. Determine the water content in the upper mantle by resolving electrical conductivity to within a factor of 2 over horizontal scales of 1,000 km.	Important	Mantle conductivity determined from time series of global magnetic measurements	Multi-point simultaneous magnetic field vector measurements with global coverage, 0.1 nT/component precision, 1 nT/component absolute; multi-year, continuous observations.	Magnetometers (e.g., SWARM), but with larger number of satellites. NOTES: This objective requires multi-point measurements from a constellation of satellites taking oriented vector magnetic measurements.	POR-8, 19 (SWARM)	TO-8
	S-5c. Quantify the heat flow through the mantle and lithosphere within 10 mW/m².	Important	Determine the heat flow through the land surface and volcanic activity	Night-time hyperspectral TIR at 30-45 m spatial resolution to determine surface heat flow to within 5 mW/m²	Imaging (e.g., MODIS)	POR-25 (ASTER, TIRS), POR-21 (MODIS)	TO-18

Page 618 Cite Bookmark

Suggested Citation: "Appendix B: Science and Applications Traceability Matrix." National Academies of Sciences, Engineering, and Medicine. 2018. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Washington, DC: The National Academies Press. doi: 10.17226/24938.

EARTH SURFACE AND INTERIOR PANEL
SCIENCE			MEASUREMENT
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Example Measurement Approaches
Societal or Science Question/Goal	Earth Science/Application Objective	Science/Application Importance	Geophysical Observable	Measurement Parameters	Method	POR	TO
			Map depth of the Curie temperature isotherm	UAV spatial magnetic anomalies, 10 nT, 10 km horizontal resolution	[aircraft total field magnetics]
*QUESTION S-6.* How much water is traveling deep underground, and how does it affect geological processes and water supplies?	S-6a. Determine the fluid pressures, storage, and flow in confined aquifers at spatial resolution of 100 m and pressure of 1 kPa (0.1 m head).	Very Important	Topography	Topography at 10 m resolution	{TerraSAR Tandem-X}. NOTES: The required radar data have been collected by the TerraSAR Tandem-X mission although the data are not publically available. A negotiated data purchase may be less costly than a new NASA mission.		COMMERCIAL
			Land-surface deformation	For seasonal variations: 1 cm/yr measured weekly at 10 m spatial sampling (which allows stacking for sub-cm secular trends)	L- or S-band InSAR, [GPS/GNSS]	POR-12 (NISAR)	TO-19
			Surface water distribution	100 m spatial, e.g., SWOT, stream gauge network, seasonally	Radar altimetry (e.g., SWOT)	POR-26, 27 (SWOT)	TO-21
	S-6b. Measure all significant fluxes in and out of the groundwater system across the recharge area.	Important	Soil moisture, snow/SWE, rainfall	1-5 km spatial, from SMAP, other radar, thermal inertia using TIR and VNIR data, and GPS reflections, weekly	Soil moisture (e.g., SMAP), rainfall (e.g., GPM)		TO-17
			Gravity	Monthly, uncertainty 1 cm water-equivalent thickness at resolution of 100 km	Gravity (e.g., GRACE-2)	POR-30 (GRACE-FO)	TO-9
			Topography	Vertical accuracy of 10 cm, resolution 1 m	SAR, lidar (suborbital)	POR-14 (ICESat-2)	TO-20
			Deformation from fluid fluxes (uses several above measurements)	Spatiotemporal distribution of subsidence/uplift at 3 mm vertical per year, 5 m horizontal, weekly. Coverage over active reservoirs.	L- or S-band InSAR, [GPS/GNSS]	POR-12 (NISAR)	TO-19
			Land-surface deformation	Spatiotemporal distribution of subsidence/uplift at 1 cm vertical, 5 m horizontal, weekly. Coverage over managed watersheds, other watersheds of interest	L- or S-band InSAR, [GPS/GNSS]	POR-12 (NISAR)	TO-19
	S-6c. Determine the transport and storage properties in situ within a factor of 3 for shallow aquifers and an order of magnitude for deeper systems.	Important	Deformation from fluid fluxes (uses several above measurements)	Spatiotemporal distribution of subsidence/uplift at 3 mm/yr vertical, 5 m horizontal, weekly. Coverage over active reservoirs.	L- or S-band InSAR, [GPS/GNSS]	POR-12 (NISAR)	TO-19
	S-6d. Determine the impact of water-related human activities and natural water flow on earthquakes.	Important	Vertical surface deformation	Spatiotemporal distribution of subsidence/uplift at 3 mm/yr vertical, 5 m horizontal, weekly	L- or S-band InSAR, [GPS/GNSS] {seismic data and production/injection data from regulatory agencies}	POR-12 (NISAR)	TO-19
*QUESTION S-7.* How do we improve discovery and management of energy, mineral, and soil resources?	S-7a. Map topography, surface mineralogic composition, distribution, thermal properties, soil properties/water content, and solar irradiance for improved development and management of energy, mineral, agricultural, and natural resources.	Important	Hyperspectral VSWIR reflectivity and TIR emissivity and surface temperature	Hyperspectral VNIR/SWIR and TIR data at 30-45 m spatial resolution and ~ weekly temporal resolution	Moderate-resolution imaging/spectometry (e.g., Landsat, Aster but with improved spectral and temporal resolution)	POR-9 (ASTER, OLI, ETM+)	TO-18
			Thermal intertia	Hyperspectral TIR data at 30-45 m spatial resolution and ~ weekly temporal resolution. Day/night measurements needed at the 12-24 hour time scale.	Imaging (e.g., MODIS, ASTER)	POR-9 (ASTER, OLI, ETM+), POR-25 (ASTER, TIRS)	TO-18
			Land-surface deformation	Spatiotemporal distribution of subsidence/uplift at 1 cm vertical, 5 m horizontal, weekly	L- or S-band InSAR with ionospheric correction, [GPS/GNSS]	POR-12 (NISAR)	TO-19
			Topography	Topographic data at 30 m postings, 25 cm vertical	{TerraSAR Tandem-X}		COMMERCIAL
			Solar irradiance	Real-time measurement of solar irradiance at better than 1 km resolution and 15-min cadence for managing solar power assisted energy grids.	Solar irradiance (e.g., GOES)