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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Hydrology and Remote Sensing Laboratory » Research » Publications at this Location » Publication #313437
Title: A satellite-based drought index describing anomalies in evapotranspiration for global crop monitoring

Author
item Anderson, Martha
item HAIN, C. - University Of Maryland
item OTKIN, J. - University Of Wisconsin

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/22/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The utility and reliability of standard meteorological drought indices based on measurements of precipitation is limited by the spatial distribution and quality of currently available rainfall data. Furthermore, precipitation-based indices only reflect one component of the surface hydrologic cycle, and cannot readily capture non-precipitation based moisture inputs to the land-surface system (e.g., irrigation, shallow groundwater tables) that may temper drought impacts or variable rates of water consumption across a landscape. Here we describe regional and global implementation of the remotely sensed Evaporative Stress Index (ESI) based on anomalies in actual-to-reference evapotranspiration (ET) ratio. Actual ET is derived via energy balance using the morning land-surface temperature (LST) rise observed with geostationary satellites, or inferred from polar orbiter measurements of day-night LST differences. In comparison with vegetation indices, LST is a fast-response variable, with the potential for providing early warning of crop stress reflected in increasing canopy temperatures. The LST-based diagnostic ET estimates used in the ESI also inherently capture ancillary moisture sources that may be poorly represented in prognostic land-surface modeling systems, potentially better characterizing actual vegetation stress and monitoring global crop conditions. A new global prototype ESI dataset using LST data from the Moderate Resolution Imaging Spectroradiometer (MODIS) will be evaluated over the 2000-2014 time period against currently used global drought indicators, with a special focus on evolution of ESI during significant agricultural droughts in the period of record. Examples of applications in predicting yield in the U.S., Brazil and Africa will be provided. Work is underway to integrate information from the Visible Infrared Imaging Radiometer Suite (VIIRS) – the MODIS follow-on sensor.