Simulating Multi-Season Past Droughts
Abstract

Abstract Author: David Lorenz and Eric DeWeaver

Abstract Title: The Role of the Land Surface and Sea Surface Temperatures in Perpetuating Drought

Abstract: In this study, we estimate the relative roles of the land surface and sea surface temperatures (SSTs) on drought persistence in 22 IPCC climate models. Drought is defined here as monthly-mean precipitation below the 20th percentile. The effect of the land surface on drought persistence over land is largest in the warm season, when it tends to dominate over the effect of SSTs on drought. The effect of SSTs on drought persistence (over land) tends to be smaller than the effect of the land surface except over some regions of the tropics and over the US (especially the southern US) in winter and spring. Because of the dominating influence of the land surface, the combined effect of both land and SSTs on drought persistence is largest in the summer over most land areas. While the role of the land surface tends to dominate in the ensemble-mean, there is considerable model-to-model variability in the strength of land/precipitation coupling-with some models having negligible influence of the land surface on drought. We also compare the IPCC climate models to observations.