TABLE 2.

Relationship between science and application goals and instrument functional requirements (as driven by the measurement requirements and science and application objectives necessary to meet the science and application goals) for a proposed set of new satellite observations

Science and application goals	Science and applications hypotheses	Measurement requirements		Instrument functional requirements
Science question: How do forest ecosystems respond to droughts in a changing climate?	There is a water content threshold beyond which tree mortality and flammability increase and productivity decline	Science requirements
		Landscape‐scale VWC of forest ecosystems at 1σ < 1‐kg/m2 accuracy	Radar reflectivity at spatial resolutions of 1–3 km	X‐band, Ku‐band, or multiple frequency (Ku‐ & L‐band) scatterometer or SAR Multiple polarization (HH, VV, HV) geostationary platform or collection of smallsats that provides observations several times a day Large swath to cover North and South Americas (50oN ‐ 50oS) at 1–3 day repeat cycle
	Major resistance to water flux in forests is determined by changes in top‐canopy water content and its link to available soil water.	Diel changes of VWC at relative accuracy of 1σ < 10%	Radar reflectivity during day and night at multiple times throughout the day
	Available soil water and the atmospheric environment will drive how well and how fast biomes adapt to climate change and shifts in seasonality	Seasonal changes of VWC at 1σ < 10% relative accuracy	Radar reflectivity at 1–3 day repeat cycle over minimum 3–5 years
Application goal: Forecasting wildfires in forests and impacts of droughts on agriculture systems	VWC determines fire fuel risk and drought resilience of crops	Application requirements
		Daily to interstorm changes of VWC at 1σ < 10% relative accuracy	Radar reflectivity at 1–3 km spatial resolution	X‐ or Ku‐band Multiple polarizations (HH, VV, HV) 1–3 day repeat cycle < 1‐km spatial resolution