青藏高原和亚洲夏季风动力学研究的新进展

亚洲夏季风环流受海陆和伊朗高原—青藏高原大地形的热力作用调控.亚洲季风所释放的巨大潜热又对大气环流形成反馈.这种相互反馈过程十分复杂,揭示其物理过程对理解气候变化格局的形成和变化以及提高天气预报及气候预测的准确率十分重要.夏季北半球副热带对流层上层环流的主要特征是存在庞大的南亚高压(SAH)以及强大的对流层上层温度暖中心(UTTM).本文介绍了温度—加热垂直梯度(T-Q_Z)理论的发展,并用以揭示SAH和UTTM的形成机制.指出沿副热带欧亚大陆东部的季风对流潜热加热及其中西部的表面感热加热和高层长波辐射冷却是导致SAH和UTTM在南亚上空发展的原因.文中还介绍了Gill模型用于上部对流层研究的局限性及解决的办法.

Recent Progresses on Dynamics of the Tibetan Plateau and Asian Summer Monsoon

The activities of the Asian summer monsoon are modulated by large-scale land-sea thermal contrast and the thermal forcing of the Iranian Plateau-Tibetan Plateau. The vast quantity of latent heat released by Asian monsoon precipitation forms a kind of feedback to the atmospheric circulation. This feedback is so complicated that it is very important to reveal the physical processes involved. Doing so will help us to understand the formation and variation of the climate pattern, as well as improve the accuracy of weather predictions and climate forecasts. The main subtropical climate system existing in the upper troposphere in boreal summer is characterized by the huge South Asia High (SAH) and the Upper-Tropospheric Temperature Maximum (UTTM). This paper introduces the development of the theory of the temperature-vertical heating gradient (T-Q_Z), and uses it to explain the formation mechanism of the SAH and UTTM. It is proven that the latent heating over the subtropical eastern Eurasian continent, the sensible heating over the central continent, and the longwave cooling in the upper troposphere are the causes of the development of the SAH and UTTM in the upper troposphere in South Asia. This paper also documents the limitation of the Gill model in studying upper-troposphere dynamics and provides a relevant solution.