Analysis of Seasonal-to-Annual Accumulating Precipitation Distribution across the Mid-Atlantic United States, 1987-2016

Track 2A: Understanding the Water Budget
Thursday, October 12, 2017, 2:00 pm – 3:10 pm

Michael Marston
Department of Geospatial and Environmental Analysis
Virginia Tech

Recent research suggests that the characteristics of precipitation are changing with a warming global climate. The inherent spatial inhomogeneity of precipitation is evident within patterns of observed precipitation changes, complicating the assessment and understanding of the impacts from changes in the hydroclimate. For many water sensitive stakeholders the importance of the distribution of precipitation through time rivals the importance of the amount of precipitation, yet temporal variability in precipitation is relatively under-studied. Daily gridded precipitation data were downloaded for the Mid-Atlantic region from 1981-2016. The precipitation data were aggregated into the four commonly-defined seasons and at the annual time scale (water year). The GINI index was used to quantitatively measure the equity with which seasonal/annual precipitation was distributed at each timescale (i.e. each season and year from 1981 – 2016). Time series of GINI values were subjected to regression analyses to examine trends in the distribution of accumulating precipitation, and were also examined against intra-seasonal streamflow variability to determine if statistical relationships exist.