INFLUENCE OF TIBETAN PLATEAU ON AIR-SEA INTERACTION OVER TROPICAL PACIFIC IN OCEAN-ATMOSPHERIC COUPLED SYSTEM

A hybrid coupled ocean-atmosphere model is designed,which consists of a global atmospheric general circulation model(L9R15 AGCM)and a simple ocean model(ZC ocean model over tropical Pacific).Using the model,experimental predictions are performed for the 1986/87 El Nino event and the 1988/89 La Nina event with and without the Tibetan Plateau respectively(called TP FORC and NTP FORC hereinafter).It is found as follows:(1)The coupled system can successfully predict the El Nino or La Nina event even if the Tibetan Plateau orography is not included in the model.The patterns of SSTA and wind anomalies in the model without the Tibetan Plateau are similar to those with the Tibetan Plateau,which further verifies the fact that ENSO process is mainly caused by the air-sea interaction in tropical Pacific.(2)However.the existence of the Tibetan Plateau exerts its influences on the intensity and duration of El Nino(or La Nina). It is unfavorable to the development and maintenance of westerly anomalies,so to some extent, restrains the development of El Nino,but favors the development of La Nina.(3)Effects of the Tibetan Plateau orography on the wind anomalies in the coupled system are different from those in uncoupled AGCM simulation.