Critical Atmospheric and Sea Surface Temperature Linkages to United States Great Plains Pluvial Years
Recent analyses have examined precipitation variability associated with the occurrence of United States Great Plains (GP) (pluvial) years. The goal of this study is to quantify primary atmospheric processes across varying temporal intervals (synoptic, subseasonal, seasonal, and annual) that yield pluvial years in the (GP) and to determine the root source of atmospheric anomalies associated with these features. Using the ERA 20th Century (ERA-20C) reanalysis data along with a variety of statistical composites and a synoptic event identification algorithm, key differences between non-pluvial and pluvial years were determined for the GP. Specifically, during Southern Great Plains (SGP) pluvial years, central tropical Pacific Ocean sea surface temperature anomalies are particularly important as SST teleconnections force an atypical Rossby wave feature over the Pacific Ocean basin, which shifts the Pacific jet stream further south leading to enhanced synoptic wave activity over the southwestern United States leading to excessive precipitation over the SGP. However, during Northern Great Plains (NGP) pluvial years, no specific pattern of oceanic or atmospheric anomalies could be found linking any global systems to excess precipitation over the NGP. Utilizing the results for SGP pluvial years, a conceptual framework was developed which details the root pathways that drive the occurrence of a pluvial year over the SGP.