The Last Glacial Maximum Tropical Western Pacific Sea Surface Temperature Difference Numerical Simulation, The Impact Of The Asian-australian Monsoon

The impact of the western Pacific SST difference between the Wang reconstruction and the Climate, Long-Range Investigation, Mapping and Prediction(CLIMAP) project' s reconstruction on Asian-austral monsoon during the Last Glacial Maxium(LGM), have been investigated using the NCAR' s CCM3 and the same boundary conditions, we design two experiments which are the W-LGM experiment and C-LGM experiment respectively, modeling results indicate that there is a significant change in Asian-Austral monsoon between the two experiments because the western Pacific SST anomaly.In summer(6~8 month average), when the tropical western Pacific SST is warmer between 140°E and 160°E, atmosphere heat of locality and Indian region all have significantly corresponding increase . Because the atmosphere heat anomaly South Africa high and the South Indian ocean meridional Hadley circulation are all intensified which make Somali cross-equatorial current stronger, on the other hand the zonal monsoon circulation in the Indian monsoon region is also strengthened, with the result of these, the Indian summer monsoon strengthen, meantime low level water vapour transport and water vapour transport convergence increase, ascending strengthen and rainfall increase in the Indian monsoon region finally: reversely in the East Asian monsoon region Australia high weaken which induces cross-equatorial current weaken about 120°E, furthermore meridional monsoon circulation south of 20°N is strengthened, zonal monsoon circulation north of 20°N is weakened, these feature show South China sea summer monsoon is strengthened, whi le East Asian subtropical continental summer monsoon is weakened, corresponding to the water vapour transport and water vapour transport convergence increase (decrease), ascending strengthen(weaken) , the rainfall increase(decrease).In winter(12~2 month average), when the tropical western Pacific SST is relatively colder, causing the local atmosphere heat significantly decrease, while the north of Australia' s increase, the cold high in the central of Asia and meridional winter circulation in the East Asia weaken, so it indicate East Asian winter monsoon weaken; in the west-north Pacific the sea level pressure intensity result in the north wind expend southly strengthen , with the effect of the low level north wind intensity causing by the meridional monsoon circulation weaken in the north of Australia , the north of Australia summer monsoon strengthen; meantime the water vapour transport, water vapour transport convergence and ascending all strengthen in the north of Australia, so the rainfall increase.