Air-sea coupling features from the warm phase to the cold phase of ENSO cycles in the seventies to the eighties

摘要

Using the sea surface temperature (SSTA) and wind anomalies (SSWA) of the tropical Pacific from January 1970 to December 1989,main spatial patterns of tropical Pacific SSTA and SSWA coupling features in the transform course from the warm phase to the cold phase of El Nino-southern oscillation (ENSO) cycles are discussed. The main conclusions are as follows: 1) air-sea coupling patterns at the mature stage of El Nino (La Nina) are main spatial ones of tropical Pacific SSWA and SSTA coupling; 2) at the mature stage of El Nino, the interaction of the anticgclonic anomaly wind,generated by the forcing of distinct meridional SSTA gradient in the northern Hemisphere tropical central Pacific, with the California cold current and SSTA is mainly responsible for weakening of El Nino; 3) the second sea temperature increase along the south American coast in the decaying course of El Nino results from the eastward movement of the weakened positive SSTA in the tropical central-eastern Pacific forced by anomalous west wind stress; 4) La Nina results from the joint effect of Walker circulation, Ekman drift and negative SSTA in the tropical central-eastern Pacific.