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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 #288995
Title: Examining rapid onset drought development using the thermal infrared based evaporative stress index

Author
item OTKIN, J - University Of Wisconsin
item Anderson, Martha
item HAIN, C - National Oceanic & Atmospheric Administration (NOAA)
item Mladenova, Iliana
item BASARA, J - University Of Oklahoma
item SVOBODA, M - University Of Nebraska

Submitted to: Journal of Hydrometeorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2013
Publication Date: 8/1/2013
Publication URL: http://handle.nal.usda.gov/10113/59967
Citation: Otkin, J., Anderson, M.C., Hain, C., Mladenova, I., Basara, J., Svoboda, M. 2013. Examining rapid onset drought development using the thermal infrared based evaporative stress index. Journal of Hydrometeorology. 14(4):1057-1074.

Interpretive Summary: In 2012, drought rapidly enveloped much of the U.S. Cornbelt, significantly impacting crop yields. This rapid onset drought event, also known as “flash drought”, was brought on by a combination of below-normal precipitation and an lingering heatwave, which drove large evaporative fluxes early in the growing season and rapidly depleted moisture reserves in the soil profile. A new remotely sensed drought index based on temporal anomalies in evapotranspiration was evaluated over several major flash drought occurrences in the U.S. over the past decade. The Evaporative Stress Index (ESI) conveyed advance warning of change in drought class status recorded in historical US Drought Monitor records by a few to several weeks. The ESI captures the major drivers of flash drought, including high temperatures, windy conditions, and extended cloudless conditions – all of which lead to high evaporative fluxes and rapid soil moisture depletion. This satellite-based index may prove to be a valuable complement to the existing drought index suite in providing early detection of rapid drought onset events.

Technical Abstract: Reliable indicators of rapid drought onset are necessary to improve the utility of drought early warning systems. In this study, the Evaporative Stress Index (ESI), which uses remotely-sensed thermal infrared imagery to estimate evapotranspiration (ET), is compared to meteorological data and United States Drought Monitor (USDM) analyses for several cases of rapid drought development that have occurred across the U.S. in recent years. Standardized change anomalies depicting the rate at which various multi-week ESI composites changed over different time intervals are computed to more easily identify areas experiencing rapid changes in ET. Overall, the results demonstrate that ESI change anomalies convey useful information about vegetation health and provide early warning of incipient drought conditions. In each case, large negative change anomalies indicative of rapidly drying conditions were either coincident with the introduction of drought in the USDM or lead the USDM drought depiction by several weeks depending upon which ESI composite and time differencing interval was used. Signals of impending drought development or intensification were usually expressed earliest in the shortest composite and time differencing intervals since they respond more quickly to rapidly changing conditions.