Spatiotemporal variability of ENSO and SST teleconnections to summer drought over the United States during the twentieth century

Presented are investigations into the spatial structure of teleconnections between both the winter El Nino-Southern Oscillation (ENSO) and global sea surface temperatures (SSTs), and a measure of continental U.S. summer droug ht during the twentieth century. Potential nonlinearities and nonstationari ties in the relationships are noted. During the first three decades of this century, summer drought teleconnections in response to SST patterns linked to ENSO are found to be strongest in the southern regions of Texas, with e xtensions into regions of the Midwest. From the 1930s through the 1950s, th e drought teleconnection pattern is found to extend into southern Arizona. The most recent three decades show weak teleconnections between summer drou ght over southern Texas and Arizona, and winter SSTs, which is consistent w ith previous findings. Instead, the response to Pacific SSTs shows a clear shift to the western United States and southern regions of California. Thes e epochal variations are consistent with epochal variations observed in ENS O and other low-frequency climate indicators. This changing teleconnection response complicates statistical forecasting of drought.