Climate Prediction: ENSO, MJO and Teleconnections
Abstract

Abstract Author: Hui Wang, Wenhong Li, and Rong Fu

Abstract Title: Intensification of summer rainfall variability in the Southeastern United States in recent decades

Abstract: The Southeastern United States is one of the fastest growing regions in the nation. Water supplies in this area are increasingly stressed, especially during summer. In the past two decades, summer droughts repeatedly struck the Southeast and had a devastating impact on this region socially and economically. The recurrence of these severe droughts raises a question as to what caused the shift of the summer rainfall variability in recent decades. In this study we will show that such intensification of summer rainfall variability is associated with significant increase in rainfall frequency and intensity in wet summers and decrease in rainfall frequency and intensity in dry summers, which are dynamically consistent with stronger variations of the upper-level jet and low-level meridional temperature gradient across the Gulf States in the recent decades. Composite analyses indicate possible causes by the tropical oceans and the extratropical atmospheric modes. Their contributions and relative importance to the shift of the summer rainfall variability over the Southeast are assessed through a multilinear regression analysis.