Numerical simulations of the interannual climate responses of East Asia to an El Niño event

With the 24-month com posite Sea Surface Temperature Anomalies (SSTAs) by 8 distinct El Niño events selected from 1949 to 1998 and the corresponding climatological SST during the same period, three numerical experiments with 10 realizations for each, such as the Control Experiment (CTRL), Tropical Ocean Global Atmosphere (TOGA) and Pacific Ocean Global Atmosphere (TOGA-NP), are carried out, so as to reveal the int erannual climate responses of East Asia to an El Niño event during its different stages and the modulations to these responses of interannual SSTAs in the North Pacific.The results show that during the summer when an El Niño event develops, there exists a significant negative Pacific Japan (PJ) wave pattern over East Asia.The the western Pacific subtropical high is weaker and shifts east ward, and East Asian summer monsoon is streng thened.In China, there is much more precipitation in North East and Jiang huai Valley, however less precipitation in North China and Changjiang River Valley.During the winter when an El Niño event is matured, the East Asian trough is deepened, winter monsoon over the north of East Asia is intensified while there is a strong anticyclone over the subtropical western Pacific.In China, there is much more precipitation in South China.During the summer when an El Niño event decays, the atmosphere circulation response and precipitation in China are nearly completely opposite to the summer when an El Niño event develops.At the same time, the inter annual SSTAs in North Pacific indeed has some modulations to the atmosphere response in East Asia to an El Niño event, and their impacts can make the simulated precipitation in China much more resembling to the observations.