Influence of Two Types of El Niņos on the East Asian Climate During Boreal Summer: A Numerical Study

The sea surface temperature anomaly (SSTA) pattern differs between the central Pacific (CP) and eastern Pacific (EP) El Niņos during boreal summer. It is expected that the respective atmospheric response will be different. In order to identify differences in the responses to these two phenomena, we examine the Community Atmosphere Model Version 4 (CAM4) simulations forced with observed monthly SST during 1979-2010 and compare with the corresponding observations.For CP El Niņo, a triple precipitation anomaly patternappears over East Asia. During EP El Niņo, the triple pattern is not as significant as and shifts eastward and southward compared to CP El Niņo. We also examine the influence of CP La Niņa and EP La Niņa on East Asia.In general, the impact of CP (EP) La Niņa on tropics and East Asia seems to be opposite to that of CP (EP) El Niņo. But there seems to be an asymmetry influence on south China between the CP (EP) El Niņo and CP (EP) La Niņa. Both of the two types of El Niņo (La Niņa) correspond to a stronger (weaker) western North Pacific summer monsoon.The sensitivity experiments support this result. But the CP El Niņo (La Niņa) may have more significant influence on East Asia summer climate than EP El Niņo (La Niņa), as the associated low-level anomalous wind pattern is more distinct and closer to the Asian continent compared to EP El Niņo (La Niņa).