末次盛冰期西太平洋海温差异对亚洲夏季风影响的数值模拟

文章利用Zhao等的模拟结果,进一步研究了在末次盛冰期(LGM)情景下汪品先和CLIMAP两种重建海洋表面温度(SST)资料差异对亚洲夏季风的影响。模拟结果表明:在LGM情景下西太平洋海域SST资料的不同对模拟的亚洲夏季风有着十分重要的作用。夏季,与CLGM方案相比,在WLGM方案中,当热带西太平洋SST较暖时,印度地区的大气热量出现显著增加,大气热量的这种变化,使得南非高压、南印度洋经向Hadley环流加强,伴随着索马里越赤道气流加强,也导致了印度季风区纬向季风环流的加强,从而造成了印度夏季风增强、降水增多;与较暖的热带西太平洋相对应,澳大利亚高压和120°E附近越赤道气流减弱,东亚季风区20°N以南经向季风环流加强、20°N以北经向季风环流减弱,指示着一个强的南海夏季风和较弱东亚副热带大陆夏季风。

MODELING THE IMPACT OF THE WESTERN PACIFIC SEA SURFACE TEMPERATURE DIFFERENCE ON THE ASIAN SUMMER MONSOON CLIMATE AT THE LAST GLACIAL MAXIUM

The climate conditions during the Last Glacial Maximum （LGM） have been always a important scientific question,documenting the characteristics of the past climates. Understanding the causes of climate change has been major challenges in studying the earth system. Both the present and past climate systems reveal the role of tropical oceans,particularly the importance of the Pacific warm pool. However,studies that aim at the impact of the western Pacific sea surface temperature （SST） anomaly on Asian summer monsoon during the LGM are rare and there still exist uncertainty of tropical western Pacific SST reconstruction in simulating the LGM climate. Thus, it is important to evaluate the effects of the different reconstructed LGM SSTs on ice age Asian summer monsoon simulations and understand what extent do the SST anomaly affect the Asian summer monsoon simulations uncertainty,which conduces to recover the climate conditions during the LGM more reasonably. 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 summer monsoon during the Last Glacial Maximum,have been investigated using the NCAR's CCM3 and the same two experiments, data as Zhao et al,the two experiments are the W-LGM experiment and C-LGM experiment respectively. General speaking the western Pacific SST in the W-LGM experiment is warmer in summer （6～8 month average） than that in the C-LGM experiment. Our modeling results indicate that there is a significant change in Asian summer 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. 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 vapor transport and water vapor transport convergence increase, ascending strengthen and rainfall increase in the Indian monsoon region finally;inversely, 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,while East Asian subtropical continental summer monsoon is weakened.