The Characteristic Variability of Boreal Wintertime Atmospheric Circulation in El Niño Events

Abstract

Abstract The influence of the Pacific sea surface temperature (SST) on the characteristic variability of boreal wintertime atmospheric circulation among El Nino events is investigated by carrying out singular value decomposition (SVD) analysis and general circulation model (GCM) experiments. From the SVD analysis of SST and 300-hPa streamfunction in the El Nino winter, the first mode associated with the strength of the El Nino mode itself has a positive trend in its time series and the second mode associated with the North Pacific SST variation includes substantial event-to-event variability. The second mode is thus important for explaining the inter–El Nino variability in atmospheric circulation. Four El Ninos among 15 El Nino events from 1950 to 1998 have a mainly positively contribution from the first SVD mode, and the other four events are influenced by the second mode as well as the first mode. The atmospheric responses related to the latter four events show the weakening of the Aleutian low and an e...