A STUDY OF CLIMATOLOGICAL ASPECTS OF FLOW FIELD AND HEAT EXCHANGE ON TROPICAL PACIFIC SURFACE IN THE EL NINO AND LA NINA EVENTS

In this paper, based on the 2°×2° grid data COADS from 1950-1987 the flow field and heat exchange anomalies on the tropical (11°S-11°N, 120°E-80°W) Pacific surface (TPS) are studied in El Nino and La Nina events. During El Nino, the zonal pressure gradient and the trade winds decrease on the TPS, the tropical convergence strengthens on the TPS, especially on the central TPS, the sensible and latent heat exchanges increase, the net longwave radiation and incident solar radiation decrease and the net gain (loss) of heat reduces (increases) on the central and eastern TPS. During La Nina the results turn out the contrary. Finally, two feedback mechanisms which include the dynamic, thermal and hydrological processes during El Nino and La Nina are summarized and a conceptive model for El Nino-La Nina cycle is given.