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AirMOSS logo North American ecosystems are critical components of the global carbon cycle, exchanging large amounts of carbon dioxide and other gases with the atmosphere. Net ecosystem exchange (NEE) quantifies these carbon fluxes, but current continental-scale estimates contain high levels of uncertainty. Root-zone soil moisture (RZSM) and its spatial and temporal hetergeneity influence NEE and contribute as much as 60-80% to the uncertainty. The goal of the Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) project is to provide a new NEE estimate for North America with reduced uncertainty by (1) providing high-resolution observations of RZSM over regions representative of the major North American biomes, (2) quantifying the impact of RZSM on the estimation of regional carbon fluxes, and (3) upscaling the reduced uncertainty estimates of regional carbon fluxes to the continental scale of North America.

Radar backscatter in soil schematic
Radar backscatter from soil
AirMOSS will utilize an airborne ultra-high frequency synthetic aperture radar capable of penetrating through substantial vegetation canopies and soil down to depths of approximately 1.2 meters. For AirMOSS, a modified version of NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) will be flown on a Gulfstream-III aircraft. Extensive ground, tower, and aircraft in situ measurements will validate root-zone soil measurements and carbon flux model estimates.

The AirMOSS RZSM benchmark datasets, a first of their kind, will be a major breakthrough over current point-scale RZSM measurements and will provide a critical set of input parameters to carbon flux models. AirMOSS science data products include RZSM at 100 m resolution (Level-2/3 RZSM), estimates of RZSM at continuous time samples through hydrologic data assimilation (Level-4 RZSM), estimates of NEE at 1 km resolution and arbitrary time scales through ecosystem demography modeling (Level-4A NEE), and upscaled North America NEE estimates at 50 km resolution (Level-4B NEE). In situ measurements taken at the study sites will also be archived, including ground sensor measurements (Level-2 IGSM), ground sensor precipitation measurements (Level-2 Precip) and atmospheric tracer flux measurements (Level-2 CFlux). The project will conclude with a new estimate of North American NEE and a quantitative assessment of the reduced uncertainty.

AirMOSS is part of the NASA Earth Ventures 1 (EV-1) program.