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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 #327411

Title: The evaporative demand drought index: Part II – CONUS-wide assessment against common drought indicators

item MCEVOY, D. - Desert Research Institute
item HUNTINGTON, J. - Desert Research Institute
item HOBBINS, M. - University Of Colorado
item WOOD, A. - National Center For Atmospheric Research (NCAR)
item MORTON, C. - Desert Research Institute
item VERDIN, J. - Us Geological Survey (USGS)
item Anderson, Martha
item HAIN, C. - University Of Maryland

Submitted to: Journal of Hydrometeorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2016
Publication Date: 6/1/2016
Citation: McEvoy, D., Huntington, J., Hobbins, M., Wood, A., Morton, C., Verdin, J., Anderson, M.C., Hain, C. 2016. The Evaporative Demand Drought Index: Part II – CONUS-wide assessment against common drought indicators. Journal of Hydrometeorology, 17: 1763-1779.

Interpretive Summary: Drought Early Warning Systems (DEWS) being developed for the U.S. and globally will benefit from indicators that reveal early signals of drought potential (driven by rainfall deficits and dry atmospheric condiitons) and actual crop stress (reflected in decreased crop water consumption and ultimately in degraded vegetation canopy cover). This paper studies staggered signals of drought that are conveyed through a variety of drought indices, and demonstrate utility of considering a suite of indicators for practical monitoring applications. The focus is on the new Evaporative Demand Drought Index (EDDI), an index highlighting the drying power (evaporative demand) of the atmosphere resulting from sunny, hot, dry and windy conditions. Response of EDDI and other drought indices to major drought events in the U.S. over the past decade is assessed. The results indicate that the EDDIS conveys valuable early warning of potential drought development, which can then be confirmed by soil moisture or crop stress indicators.

Technical Abstract: Precipitation, soil moisture, and air temperature are the most commonly used climate variables to monitor drought, however other climatic factors such as solar radiation, wind speed, and specific humidity can be important drivers in the depletion of soil moisture and evolution and persistence of drought. This work provides an assessment of the Evaporative Demand Drought Index (EDDI) at multiple time scales for several hydroclimates as a companion study to Hobbins et al. (2015) by examining EDDI and individual evaporative demand components as they relate to the dynamic evolution of flash drought over the central US, characterization of hydrologic drought over the western US, and comparison to commonly used drought metrics of the US Drought Monitor, Standardized Precipitation Index (SPI), Standardized Soil Moisture Index (SSI), and the Evaporative Stress Index (ESI). Two main advantages of EDDI over other drought indices are that it is independent of precipitation (similar to ESI) and it can be decomposed to identify the role of individual evaporative drivers for drought case studies. At short time scales, spatial distributions and time series results illustrate that EDDI often indicates drought onset well in advance of the USDM, SPI, and SSI. Our results illustrate the benefits of physically based evaporative demand estimates, and demonstrate EDDI’s utility and effectiveness in an easy-to-implement agricultural early warning and long-term hydrologic drought monitoring tool that has potential application to seasonal forecasting and fire-weather monitoring.