Fall 2015
Colloquia are held on Fridays at 11:30 a.m. in Cullimore Lecture Hall II, unless noted otherwise. Refreshments are served at 11:30 am. For questions about the seminar schedule, please contact Yassine Boubendir.
Date: November 13, 2015
Speaker: Richard Seager
Lamont-Doherty Earth Observatory,
Columbia University
Title: "The Atmosphere-Ocean Dynamics of North American Droughts"
Abstract:
Persistent, multiyear droughts are a frequent occurrence in western North America. In all cases during the period of instrumental records these have been caused by equally persistent variations in the sea surface temperatures (SSTs) of, primarily, the tropical Pacific Ocean and, secondarily, the tropical North Atlantic Ocean. This includes the famed Dust Bowl drought of the 1930s, the severe southwest drought of the 1950s and the drought that has effected the southwest to varying degrees since 1999. The atmospheric dynamics whereby SST anomalies in the tropics force changes in the mean atmospheric flow and storm tracks that create dry conditions in the southwest and Plains will be explained. The role that atmosphere-land surface-dust interactions played to worsen drought during the Dust Bowl will also be discussed. Climate change due to rising greenhouse gases is confidently expected to lead to a drier southwest, and wetter northeast, of North America and the dynamical and thermodynamical causes of this will be discussed together with an assessment of the causes of the ongoing western drought.