Role of Pacific Sea Surface Temperatures in U.S. Great Plains Pluvial Years

Building on previous work investigating United States Great Plains (GP) wet (pluvial) years, this study utilized ERA 20^th Century (ERA-20C) reanalysis data to narrow the knowledge gap inherent in GP precipitation variability. The goal of the study was to diagnose atmospheric processes determined to be the primary attributable cause of GP pluvial years and to find the root source of the atmospheric anomalies. Using a variety of statistical composites and a synoptic event identification algorithm, key differences between non-pluvial and pluvial years were determined for the GP. Results show that during Southern Great Plains (SGP) pluvial years, central tropical Pacific Ocean sea surface temperature anomalies were particularly important. These sea surface anomalies are coincident with a Rossby wave anomaly over the Pacific Ocean basin, which shifts the Pacific jet stream further south. During Northern Great Plains (NGP) pluvial years no specific pattern of oceanic or atmospheric anomalies could be found linking any global systems to the excess precipitation over the NGP. Utilizing the results for SGP pluvial years, a conceptual model was developed detailing the identified root pathway for the occurrence of a pluvial year over the SGP. Overall, results from this study show the importance of the identified SGP atmospheric anomaly signal from previous work and the potential for predictability of such events.