Examining flash drought development using the Evaporative Stress Index (ESI)

In recent years, the development of severe drought conditions over a short period of time has attracted increasing attention within the drought and agricultural communities since these events, which are commonly referred to as “flash droughts”, can adversely effect plant health and subsequent crop yields. In this study, the evolution of several flash drought events across the central U.S. will be examined using meteorological data and a new drought index that is based on the remote sensing of evapotranspiration (ET). The Evaporative Stress Index (ESI) quantifies anomalies in the ratio of potential to real ET using the Atmospheric-Land Exchange Inverse (ALEXI) surface energy balance model and thermal band imagery from geostationary satellites. Preliminary investigations of historical ESI data from 2000-2011 indicate that it can provide useful information about the onset of drought conditions. For instance, when normalized anomalies in the ESI decrease rapidly during consecutive weeks, drought conditions are more likely to rapidly develop during subsequent weeks unless rainfall or cooler temperatures prevent drought development.