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Quick Drought Response Index (QuickDRI)

   

    Quick Drought Response Index (QuickDRI) for
    the last week of May 2017 (week 22)

The Quick Drought Response Index (QuickDRI) is a weekly geospatial model and dataset that is an indicator of short-term dryness across the conterminous United States (CONUS). The development of the QuickDRI data was a collaborative effort by scientists at the USGS EROS Center, the National Drought Mitigation Center (NDMC) and Center for Advanced Land Management Information Technologies (CALMIT) at the University of Nebraska-Lincoln, the U.S. Department of Agriculture Agricultural Research Service, and the NASA Goddard Space Flight Center.

The QuickDRI modeling methodology involves the integration of satellite vegetation, hydrologic, climate, and biophysical data.  Weekly varying input data include the Standardized Vegetation Index (SVI) and the Start of Season Anomaly (SOSA) calculated from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on the Aqua platform, the 4-week Evaporative Stress Index (ESI) Anomaly, the Variable Infiltration Capacity (VIC) 1-month Anomaly (VMA) land surface model, and the 1-month Standardized Precipitation Index (SPI).  Of the weekly input datasets, the SVI and SOSA are processed in the QuickDRI system and the ESI, VMA, and SPI are acquired from offsite production systems.  QuickDRI also ingests several biophysical variables to assist the model to identify rapidly changing conditions, including a digital elevation model, the MODIS Irrigated Agriculture Dataset, the National Land Cover Database, and Root-zone Available Water Storage Capacity. 

The SVI is a calculation of the probability of a relative vegetation condition based on a Z-score calculation from the weekly eMODIS Normalized Difference Vegetation Index.  Weekly NDVI averages (over the period 2003 to 2016), standard deviations, and a probability look-up table are involved in calculating the SVI.  A Z-score calculation is done pixel by pixel across the image.  The Z-score is a deviation from the average in units of the standard deviation for each pixel for each week and each year. Recalculation of historical weekly averages and standard deviations is planned to be updated yearly but is not provided.

In operation, the QuickDRI and SVI raster data for CONUS are produced as seamless gridded raster products in GeoTIFF format with a 1-km spatial resolution.  The production schedule is performed weekly using the latest input datasets, and output data are usually posted each Monday by 11:00 a.m. CT.

QuickDRI is a weekly operational product generated within 24 hours of an Aqua MODIS overpass time. QuickDRI incorporates data from eMODIS expedited NDVI composites and provisional near-real-time climate data accessed from the Applied Climate Information System.  Due to the rapid production schedule, the input satellite and climate datasets are not subject to extensive quality assurance, and input data errors may produce errors in QuickDRI.  While the USGS makes every effort to provide accurate and complete information, users should be aware of this potential limitation in QuickDRI accuracy.

Digital Products

Weekly QuickDRI data and associated products are available for download through EarthExplorer for the data held in the USGS archive. The download package includes a set of four items contained in a tar file:

1. QuickDRI browse graphic in JPG format
2. QuickDRI product in GeoTIFF format
3. Standardized Vegetation Index (SVI) product in GeoTIFF format
4. Metadata for the eMODIS 7-day composite used to generate the QuickDRI product

Additional Information:

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Contact Information for User Assistance

U.S. Geological Survey (USGS)
Earth Resources Observation and Science (EROS) Center
47914 252nd Street
Sioux Falls, SD 57198-0001

Phone Number: 605-594-6151
Toll Free: 800-252-4547
Fax: 605-594-6589

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