Updating and Enhancing the National Drought Mitigation Center's Drought Risk Atlas

Updating and Enhancing the National Drought Mitigation Center’s Drought Risk Atlas

Brian Fuchs, National Drought Mitigation Center, University of Nebraska-Lincoln, Lincoln, NE

Mark Svoboda, National Drought Mitigation Center

Erica Johs, National Drought Mitigation Center

William Sorensen, High Plains Regional Climate Center

Stephen Shield, National Drought Mitigation Center

Claire Schirle, National Drought Mitigation Center

 

With the National Drought Mitigation Center’s (NDMC) release of the Drought Risk Atlas (DRA) (http://droughtatlas.unl.edu/) in 2013, an on-line resource of drought history and drought climatology was made available for 3,059 locations across the continental United States.  The DRA currently provides calculations for several indices that include the Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI), the Palmer Drought Severity Index (PDSI), the self-calibrated Palmer Drought Severity Index (sc-PDSI), deciles, and the United States Drought Monitor.  In calculating these indices, the NDMC worked with the High Plains Regional Climate Center (HPRCC) to produce a serially complete data record for each station using vetted estimation programs and techniques developed to fill in missing observations.  The estimation of data was minor as most stations were better than 95 percent complete.  Each station used in the DRA has at least 40 consecutive years of data with no more than two months of missing data at any time in its record. A unique period of record was established for each station used in the DRA and with these criteria, the best long-term climate stations in the National Weather Service’s Cooperative Observer Program (COOP) network were used to get an accurate assessment of drought occurrence and return probabilities using multiple drought indices.  This work resulted in the construction of an important serially complete database that can be used as a resource in any climate study and is a valuable research tool resource.

With a very strict initial station criteria, it became apparent that many of the stations excluded from the DRA also contained little missing data and were good climatological stations.  Recent work has allowed the NDMC to revisit the stations in the COOP network and identify these stations for inclusion into the DRA.  All of the COOP stations were rescreened and 223 additional stations were identified which met the original criteria, while another 910 stations were identified as being good stations that have gaps in their data records, but were still determined to be very good quality climatological stations.  With over 1100 new stations being included, 4,192 stations have now been identified for inclusion in the DRA.  The stations are again being finalized to serially complete status by the HPRCC and all indices and derivative products will also be updated.  With a 37 percent increase in the number of COOP stations identified, the DRA becomes an even stronger tool for analyzing past drought events and analyzing the risk of future droughts based on these past occurrences.

Additional enhancements to the Drought Risk Atlas being considered are the inclusion of historical streamflow data, the inclusion of SNOTEL data, trend analyses of drought using the various indices and gridded maps of each index.  All of this work is again being driven by a serially complete dataset, which is a valuable research tool in and of itself.