The Study On Response Of Climatic Variability For East Asian Monsoon To SSTA

Based on Hadley climate center of monthly mean sea surface temperature (SST) and the Chinese 160 stations monthly mean temperature and precipitation data, etc. during 1951—2012, the reasons between EAWM and EASM with multiple basins of sea surface temperature anomaly (SSTA) are analyzed by the method general equilibrium feedback (GEFA) of recent development, combined with the methods of EOF analysis, correlation analysis and so on, and by determining the EAWM or EASM on the response to significant SSTA mode by atmospheric circulation anomaly, exploring the possible mechanisms of SSTA affects monsoon exception occurs.Based on GEFA and EFA method,making the difference between the monsoon anomalies of a single basin SSTA and SSTA response to multiple basin.The results indicate that:(1) The first mode SSTA of tropical Indian Ocean (IOBM,95% confidence level) and the third mode SSTA of tropical Pacific Ocean (TP3,90% confidence level) affect the EWAM significantly, relative variance contributions are 18.14% and 9.19% respectively, when TI1 in cold consistently or TP3 in positive phase, the EAWM get stronger. As to EASM, when tropical Indian Ocean (IOBM,95% confidence level) in cold consistently or the second mode SSTA of North Atlantic Ocean (NA2,90% confidence level) in positive phase, the EASM get stronger, relative variance contributions are 6.34% and 4.23% respectively. That is to say, IOBM has a significant impact on EAWM and EASM.(2) Key ocean SSTA by forcing the change of the Siberian high and the Aleutian low to affect the EAWM intensity. Cooled SSTA of TIO1 or Pacific negative phase of the El Nino Modoki SST anomaly cause high level convergence, low level divergence in Siberia, and high level convergence is stronger than low level divergence, rising its sea level pressure (SLP) observably; divergence of the Aleutian in the both high and low level, reduce the SLP. High level divergence, low level convergence in the equatorial western Pacific Ocean, SLP becomes lower.(3) When the tropical Indian Ocean basin consistent cooling, local convection is abate, inspire east to Kelvin wave of cold,make the west Pacific westerly anomaly, produce anomalous cyclonic circulation, westerly anomaly response in monsoon trough, meiyu front area of easterly anomaly response, boosting the EASM. When SSTA forcing NA2 have a positive phase, the Yangtze river region,500hPa for anomaly vertical velocity response, precipitation reducing, air cooling, meiyu front area appears lower troposphere zonal east wind abnormal response, boosting the EASM.(4) Based on balance feedback method(EFA) of monsoon to the diagnosis of single SSTA mode response, and found that the EAWM on the first and third SSTA of the tropical Pacific, and the first tropical Indian Ocean mode response is obvious. The reason why the tropical Pacific first mode in EFA diagnosis was ’borrowed’ from the IOBM and the second southern Indian Ocean mode. The reason why EASM response to NAlobvious is’borrowed’ the influence of IOBM and IOD mode in the Indian Ocean.