印度半岛热力变化对亚洲季风环流异常的影响

The Impact of Surface Thermal Variation over Indian Peninsula on Asian Monsoon Circulation Anomaly

海陆热力差异的季节性变化是季风产生的原始驱动力,因此海洋和大陆任何一方的变化必然会影响季风环流出现异常。本文探讨了欧亚大陆高、低层气温、南亚大陆和印度洋之间海陆热力差异的变化特征,发现南亚大陆的印度半岛区域下垫面的季节性增暖出现最早,其增暖从春季就开始出现,比对流层上层增暖偏早约两个月,相应的低层经向海陆温度梯度由冬季型转为夏季型最早的区域出现在80°E附近。进一步分析了印度半岛下垫面热力异常的变化特征及其与季风环流异常的关系,初步揭示了南亚区域高、低层气温变化的相互联系,发现印度半岛下垫面的迅速增温引起了大气的强感热加热,进而影响高、低层季风环流的异常变化。结果表明,春末夏初印度半岛暖下垫面的加热作用有利于亚洲夏季型季风环流建立偏早,同时也有利于亚洲夏季季风环流的加强,而冷下垫面的作用则相反。

Land-sea thermal contrast is a leading factor to the forming and maintain of monsoon circulation,so either the thermal variation over ocean or land will cause anomalous monsoon.Previous many works have mainly aimed at the effect of temperature gradient reversal resulting from seasonal warming in upper troposphere and rising heating over Tibet Plateau on monsoon.In this paper,the daily and monthly temperature fields and thermal contrast between India ocean and South Asian land were firstly investigated.The results showed that the earliest seasonally warming occurs in spring over Indian island,which is earlier two months than the warming in upper troposphere,and accordingly the reversal of meridional temperature gradient firstly appears near 80°E.Further,the thermal variation over Indian peninsula and its influence on monsoon circulation were further explored.The results indicated that the temperature variations in upper and lower tropospheres are basically consistent,it is found that the thermal anomalies over Indian peninsula influence on monsoon circulation by increasing sensible heating.In last spring and early summer,warm surface temperature over Indian peninsula make for early appearance of summer monsoon circulation,and vice versa.