U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Hydrology and Remote Sensing Laboratory: Beltsville, MD
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                                    Software
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Northeast Area Beltsville, Maryland (BARC) Beltsville Agricultural Research Center Hydrology and Remote Sensing Laboratory Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications
- People
- Research Sites
- Pesticide Volatilization
- Watershed Modeling
- Climate Change
- Soil Moisture
- Drought and ET
- HRSL Brochure

Title:   Author  item
                                            HOBBINS, M. - University Of Coloradoitem
                                            WOOD, A. - National Center For Atmospheric Research (NCAR)item
                                            MCEVOY, D. - Desert Research Instituteitem
                                            HUNTINGTON, J. - Desert Research Instituteitem
                                            MORTON, C. - Desert Research Instituteitem
                                            VERDIN, J. - Us Geological Survey (USGS)item
                                            Anderson, Marthaitem
                                            HAIN, C. - University Of Maryland
  Submitted to: Journal of Hydrometeorology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 4/20/2016
                                    Publication  Date: 6/1/2016
                                    Citation: Hobbins, M., Wood, A., Mcevoy, D., Huntington, J., Morton, C., Verdin, J., Anderson, M.C., Hain, C. 2016. The evaporative demand drought index: Part I 1 – Linking drought evolution to variations in evaporative demand  . Journal of Hydrometeorology. 17(6):1745-1761. https://doi.org/10.1175/JHM-D-15-0121.1.DOI: https://doi.org/10.1175/JHM-D-15-0121.1                                                              
                                Interpretive Summary: Rapid onset, or "flash", drought events are caused by a combination of lower-than-average rainfall and hot, dry and windy conditions that accelerate evaporation of soil moisture into the atmosphere.   The drying power of the atmosphere is called the evaporative demand, and it can be mapped using standard meteorological datasets describing air temperature, vapor pressure, wind speed and solar radiation.   Early signals of potential for flash drought onset might be revealed in maps of evaporative demand, providing valuable early warning for farm management or famine relief decision making.  This hypothesis was tested in this paper, investigating behavior of a new Evaporative Demand Drought Index (EDDI), describing anomalies in evaporative demand over the continental U.S. over the past decade.  The EDDI was compared with several other drought indicators, including the U.S. Drought Monitor, and found to provide early precursor signals preceeding major flash drought events.  The EDDI can be combined with indicators describing decrease in soil moisture and increase in crop stress, providing evidence that the atmospheric potential for drought had progressed to actual agricultural drought conditions on the ground.   Together, these indices paint a more complete picture of how flash drought events evolve and what the expected impacts will be.
                                Technical Abstract: Many operational drought indices focus primarily on precipitation and temperature when depicting hydroclimatic anomalies, and this perspective can be augmented by analyses and products that reflect the evaporative dynamics of drought. We leverage the linkage between atmospheric evaporative demand (E0) and actual evapotranspiration (ET) in a new drought index based solely on E0—the Evaporative Demand Drought Index (EDDI). EDDI measures the signal of drought through the response of E0 to surface drying anomalies that result from two distinct land surface-atmosphere interactions: (1) a complementary relationship between E0 and ET that develops as moisture becomes limited at the land surface, leading to ET declining and increasing E0, as in sustained droughts; and (2) parallel ET and E0 increases arising from increased energy availability leading to surface moisture limitation, as in flash droughts. To calculate EDDI from E0, we use a long-term, daily reanalysis of reference ET estimated by the American Society of Civil Engineers (ASCE) Standardized Reference ET equation using radiation and meteorological variables from the North American Land Data Assimilation System (NLDAS) phase-2. EDDI is derived by deriving empirical probabilities of aggregated E0 depths relative to their climatologic means across a user38
specific time period and normalizing these probabilities. Positive EDDI values then indicate drier than normal conditions and the potential for drought. EDDI is a physically based, multi-scalar drought index that that can serve as an indicator of both flash and sustained droughts, in some hydroclimates offering early warning relative to current operational drought indices.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov