南海季风爆发期间大气环流结构与对流热量、水汽输送特征

Atmospheric Structure and Characteristics of Convection Transport of Heat and Moisture during Monsoon Onset over South China Sea

利用中国南海季风试验（SCSMEX）区1998年5～6月“科学1号”和“实验3号”观测船得到的一天4次加密探空资料，重点分析了南海北部地区（15～25°N，108～122°E）夏季风爆发前后大气环流的动力、热力和湿度场分布与海洋对流热量和水汽输送特征。结果表明，南海北部季风爆发前后的大气动力场、温湿场出现快速而明显的变化。季风爆发前，南海北部地区高层辐合、低层辐散，以下沉气流为主；季风爆发后，在200hPa左右高层辐散，而在900-950hPa左右低层辐合，并出现强上升气流。这种动力场的显著变化引起温度、湿度场的改变，直接导致南海对流的快速发展，对流活动伴随着剧烈的热量和水汽垂直输送和转化。

Using the sounding data of four times a day in May and June, 1998 collected on two observational ships, that is Kexue 1 and Shiyan 3, during the South China Sea （SCS） Monsoon Experiment （SCSMEX）, the structure of dynamics, temperature and moisture, and the characteristics of oceanic convection transport of heat and moisture were analyzed. The results show that the atmospheric dynamics, temperature and humidity experienced a rapid and obvious change after monsoon onset over the SCS. In the period of pre-monsoon, the upper air was convergent and the lower air was divergent showing strong downward air current in the northern SCS. After monsoon onset, the upper air is divergent at 200 hPa and the lower air was convergent between 900 and 950 hPa, showing a strong upward air current. This noticeable change in dynamic field causes the changes of temperature and humidity field, and directly leads to the rapid development of convection over northern SCS, and the convective activity was accompanied by vertically strong transport and transformation of energy and water vapor.