The Southern Oscillation Revisited: Sea Level Pressures, Surface Temperatures, and Precipitation

An update is given of the global correlation and regression patterns of sea level pressure associated with the Southern Oscillation, based upon the reanalyses from the National Centers for Environmental Prediction–National Center for Atmospheric Research for 1958–98, a period independent of that of early work. Features over the oceans are better defined than was previously possible and most features prove to be robust, although climate changes such as the 1976 climate shift have evidently altered some important relationships, such as those with Southeast Asia. Associated surface temperature patterns are also shown over the same interval and reveal striking symmetry about the equator. For El Niño, the patterns emphasize the associated broad warming over the tropical central and eastern Pacific, as well as along the west coast of the Americas extending into high latitudes of the Pacific in both hemispheres, and cooling in the central North and South Pacific. Precipitation patterns associated with the Southern Oscillation are given based upon the post-1979 period to include satellite data over the oceans, which emphasizes that the main changes are for a global redistribution of precipitation, so that solely land-based perspectives are biased. While annual mean patterns reveal much of the geographic structure associated with the Southern Oscillation, important seasonal variations are present, especially for sea level pressure and precipitation.