Trends and Climate Sensitivity of Precipitation Correlation Distances Across the Contiguous U.S.

Abstract

The spatial scale over which seasonal precipitation is autocorrelated could impact both data set development and water resources management, but spatial and temporal variability in these relationships and their potential changes have not been systematically evaluated. Here, we quantify changes in the length scale of seasonal precipitation correlations using daily values from 19,786 precipitation gauges from 1950 to 2019 across the contiguous United States. Annual precipitation correlation distance (PCD) is shorter in the western than eastern U.S., and shorter in summer than winter. In summer, PCD significantly decreased by 0.37 km/yr over the 70-year study period in the Northwest, Northern Rockies and Plains, and Upper Midwest regions. Declines were smaller in other seasons, and PCD had spatially variable climate dependencies. Decreases in PCD suggest an increase in seasonal precipitation spatial variability and a shift toward more convective dominating precipitation, and could challenge precipitation interpolation exercises in sparsely gauged areas.