Numerical Simulations of Anomalous Winter Monsoon in East Asia Exciting ENSO
Li Chongyin and Mu Mingquan (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing100080)
In this paper, we investigate influences of anomalous winter monsoon in East Asia on the equatorial Pacific Ocean with tropical Pacific ocean model (OGCM) and coupled ocean-atmospheric general circulation model (CGCM), respectively. The results clearly show that continually stronger winter monsoon is able to lead to obviously positive sea surface temperature anomaly (SSTA) in the equatorial central and the eastern Pacific Ocean and its horizontal distribution is well identical with the large-scale feature of natural El Ni[AKn～D]o events; however, consecutively weaker winter monsoon will make SST decrease in that area and its pattern can be compared to La Nia. Therefore, numerical experiments further prove the conclusion unraveled based on the observed data diagnoses and theoretical analyses in the previous studies — anomalous winter monsoon in East Asia is an important exciting mechanism of ENSO; the simulation results also show that the anomalous Kelvin waves in the ocean and the anomalies of atmospheric intraseasonal oscillation caused by anomalous winter monsoon play an important role in the occurrence of ENSO as that shown in the observation.