Precursors of the Southern Oscillation

Abstract

AbstractEvidence is presented of the existence of three largely independent precursors of changes in the Southern Oscillation (SO). In a region of the south‐east Pacific, anomalously high SST, low pressure, low cloudiness and weak winds tend to occur in December‐February (DJF) prior to a year of low SO index. In the equatorial Atlantic, anomalously warm sea in DJF tends to follow a period of low SO index and precede a year of high index. Cold SST in a region near northern Australia is associated in every season with a trend towards warmer SST in the equatorial east Pacific, and in most months with anomalous westerly winds in the equatorial west Pacific. Plausible physical scenarios are proposed to explain the relationships.