Mapping Evapotranspiration and Drought at local to Continental Scales using Thermal Remote Sensing

Using thermal-infrared imagery from the Geostationary Operational Environmental Satellites (GOES), a fully automated inverse model of Atmosphere-Land Exchange (ALEXI) has been used to model daily ET and surface moisture stress over a 10-km resolution grid covering the continental United States. Monthly anomalies in the ALEXI moisture stress fields show good spatiotemporal correspondence with standard drought metrics, but at significantly higher spatial resolution due to limited reliance on ground observations. In a disaggregation mode (DisALEXI), the model can also generate moderate to high-resolution (10⁰-10³ m) flux maps over targeted scenes using thermal images from platforms like Landsat and MODIS. In combination, the ALEXI/DisALEXI package facilitates scalable ET and stress mapping in a framework like Google Earth, zooming in from the continental scale to sites of specific interest. Given NASA´s decision to discontinue TIR imaging capabilities on the Landsat Data Continuity Mission, however, we face an impending gap in our ability to map moisture status at the critical sub-field scale (~100 m), which will adversely affect active water management and drought monitoring applications worldwide.