Numerical Simulation of the Atmospheric Response to the Time-Varying El Niño SST Anomalies during May 1982 Through October 1983

Abstract

A general circulation model was first integrated for 25 months with monthly climatological boundary conditions of sea surface temperature (SST), soil moisture, sea ice and albedo. Starting from day 165 of this ?control? integration, which corresponds to 1 May, another 18-mouth integration was carried out in which all the boundary conditions were the same as in the control run, except that the observed monthly SST anomalies for May 1982?October 1983 were added to the climatological values in the Pacific from 40°S to 60°N. Monthly and seasonal means of the differences between the two integrations were compared to the observed atmospheric anomalies during the record El Niño wann SST event of 1982?83. The evolution of the strong atmospheric anomalies observed in the tropics was well simulated for the entire 18-month period. There were considerable differences in the extratropics between simulated and observed seasonal anomalies. The highly successful anomaly simulation in the tropics is encouraging in light of the recent successes of tropical ocean modelers and suggests the possibility of obtaining useful long-term climate forecaste from a coupled ocean-atmosphere model.