Characterizing Precipitation Correlation Distance (PCD) in the Contiguous United States

Climate change is affecting and will continue to affect weather patterns across the globe (Crimmins et al., 2023), introducing a layer of complexity to our understanding of precipitation variability. Precipitation variability increases uncertainties in precipitation measurements and, in a warming climate, the variability of precipitation is projected to increase (Pendergrass et al., 2017). Appropriate understanding of the spatiotemporal variability of climate-scale seasonal to annual precipitation and its changes could help improve gap-filling approaches used in gridded data product development. Here, we characterize the spatiotemporal variability of precipitation in the contiguous United States (CONUS) by introducing the precipitation correlation distance (PCD), which is the distance over which seasonal precipitation is correlated. We use daily precipitation data from the serially complete Earth (SC-Earth; Tang et al., 2021) dataset for just under 20,000 precipitation gauges from 1950 to 2019 across CONUS to determine annual and seasonal precipitation anomalies at each gauge. Over a grid of 64 km resolution, we apply a spatial statistics modeling approach to determine the PCD, the range estimate of the kriging analysis, in a 400-km radius circle centered on each grid cell. The spatial extent of annual PCD is shorter in complex than simple terrain, with the greatest spatial correlation in the summer. PCD decreased over the 70-year study period in summer, fall, winter, and spring (Sen’s slope p < 0.05) in 48%, 16%, 5.6%, and 11% of grid cells, respectively. PCD decreases were largest in the summer in the Northern Rockies and Plains, Northwest, and Upper Midwest regions. Findings of declining PCD could inform gap-filling approaches that assume constant PCD and network design of gauges in places with high or increasing spatial variation. These findings could also be used to evaluate climate models and inform the development of gridded precipitation products.