Evaporative Demand Drought Index (EDDI)

Plot EDDI Time Series of the Continental U.S.

EDDI plot for Boulder, CO

This webtool allows a user to generate historical (1980-latest complete year) timeseries data of the Evaporative Demand Drought Index (EDDI) for a specified region in the Continental United States. The time series is generated as a table for different timescales, i.e. 1 to 12 months of integrated evaporative demand at the end of a given month. This tool also allows users to generate time series plots with user specified timescales.

1 Region
Drag to move map; SHIFT-Drag to select region
N
W   E
S
2 Plot Options
Averaging Period (Months)? Ending Month?
(ending month includes values through the end of that month)
Enter Region Title (OPTIONAL: Used in the plot title: default is the lat/lon range)

Description of Time-Series Data and Plot

This page generates historical (1980-latest complete year) time-series data of EDDI across a user-selected region and timescale. You can select your region as a rectangular area by directly entering latitude and longitude values or by selecting the area in the adjacent map. The main output is a table with EDDI time series for timescales of 1 to 12 months. A plot will also be generated with user- (or default-) entered month and averaging period, which will accompany another table showing the time-series data with user-defined specifications. On the output page, you will have an option to readily replot EDDI time series with different specifications.

To estimate evaporative demand (E0), this tool uses daily reference evapotranspiration based on the Penman Monteith FAO56 method for tall (0.5m) reference crop that is available from the the operational North American Land Data Assimilation System (NLDAS-2) dataset. The spatial resolution of the data is 1/8th degree in latitude and longitude (i.e. approximately 12km). Daily E0 values are then aggregated to monthly values, and spatial averaging is done before monthly EDDI values are computed. At any point in time, there is large spatial variability in EDDI across CONUS. For generating these time series for meaningful assessment, we generally recommend that users select as small an area as possible (e.g., county, climate division, small watersheds), including point locations (i.e., by using a single latitude value in both the N and S boxes, and a single longitude value in both E and W boxes. for bounding the region, thereby getting the time series for just a single representative 12km x 12km pixel).

The main output table also includes reference evapotranspiration value (in mm) for each month used to calculate EDDI. The absolute values of E0 are highest during the warm season, during which there is also a heightened risk of water stress on the land surface in water-limited regions. For drought-related impacts, users can use time series of different EDDI timescales to compare with their own historical impacts data.

For further assistance or technical advice on the use of these timeseries data for research applications please contact Mike.Hobbins@noaa.gov.

This is a Research and Development Application