伴随南海季风爆发区域尺度环流演变机理的诊断分析和数值模拟

利用1957－1998年NCEP／NCAR候平均再分析资料，分析伴随南海夏季风爆发中南半岛和南海地区环流系统的演变，揭示该地区热力特征与南海夏季风爆发之间的可能联系。结果发现，不同高度上标志着南海爆发的环流系统如500hPa上的副热带高压、200hPa上的南亚高压以及850hPa 上的孟加拉湾低槽等系统在南海季风爆发期间具有显的变化特征，对流层中高层以上的环流系统反映了大尺度环流的季节变化特征，而对流层低层环流系统的变化可能与局地特征具有密切关系。从中南半岛和南海两个地区地面感热和潜热加热与该地区温压场变化之间的关系上看，中南半岛地区的热力作用对南海季风爆发期间区域环流系统演变具有重要作用，数值试验结果进一步证实了这一点。

Diagnostic and Numerical Study of Evolutions of Regional Circulation System Associated with the South China Sea Monsoon Onset

The NCEP/NCAR reanalysis data from 1957-1998 are used to study the regional circulation evolutions associated with the South China Sea monsoon onset in the South China Sea and Indochina peninsula region and to reveal the connections between the thermal characteristics in this region and the South China Sea monsoon onset. It is found that the regional circulation systems, such as the subtropical high at 500 hPa, the South Asia high at 200 hPa, and the trough over the bay of Bengal at 850 hPa, change significantly during the South China Sea monsoon onset. The evolution of circulation systems in the upper troposphere reflects the seasonal variation of large scale circulation and the change of lower level circulation system is related to the local thermal characteristics. The analyses of the sensible and latent heat on the ground associated with temperature and geopotential height fields show that the heating of the Indochina peninsula plays an important role in the evolution of regional circulation systems during the South China Sea monsoon onset, which is further verified by the numerical experimental results.