Influence of two types of El Nios on the East Asian climate during boreal summer: a numerical study

The sea surface temperature anomaly pattern differs between the central Pacific (CP) and eastern Pacific (EP) El Nios 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 simulations forced with observed monthly sea surface temperature during 1979-2010 and compare with the corresponding observations. For CP El Nio, a triple precipitation anomaly pattern appears over East Asia. During EP El Nio, the triple pattern is not as significant as and shifts eastward and southward compared to CP El Nio. We also examine the influence of CP La Nia and EP La Nia on East Asia. In general, the impact of CP (EP) La Nia on tropics and East Asia seems to be opposite to that of CP (EP) El Nio. However, the impacts between the two types of La Nia are less independent compared to the two types of warm events. Both types of El Nio (La Nia) correspond to a stronger (weaker) western North Pacific summer monsoon. The sensitivity experiments support this result. But the CP El Nio (La Nia) may have more significant influence on East Asia summer climate than EP El Nio (La Nia), as the associated low-level anomalous wind pattern is more distinct and closer to the Asian continent compared to EP El Nino (La Nina).