第一次全球大气研究计划试验期间华南前汛期暴雨过程及其环流特征的诊断研究

Heavy Rainfalls in South China and Related Circulation during First GARP Global Experiment Period

对 1979年第一次全球大气研究计划试验 (FGGE)期间华南前汛期 3次暴雨过程及其环流特征进行了诊断研究。发现 :(1) 3次暴雨过程均与锋面活动有关 ,每次锋面过程都与锋生区对应 ,暴雨多见于锋前暖区内。锋面的特征既不同于冬季的冷锋 ,又不同于夏季长江流域的梅雨锋。 (2 )对视热源和视水汽汇作了计算 ,发现 3次暴雨过程中 ,华南地区的视热源和视水汽汇项有明显作用 ,积云对流所造成的对流凝结加热作用很重要。 (3)华南前汛期暴雨与南海季风有密切关系。 1979年FGGE期间南海季风 3次向北推进 ,与 3次暴雨过程有直接的联系。 (4 )对这 3次降水过程的水汽来源作了分析 ,发现除孟加拉湾外 ,南中国海亦是重要的水汽供应源地。 (5)对云系的分析表明 ,华南上空的 β中尺度对流云团为暴雨的发生提供了有利条件。

During the First GARP Global Experiment (FGGE) period of 1979, about three heavy rainfalls occurred in South China In this paper, a diagnostic study is conducted The conclusions are the followings: (1) The heavy rainfalls during FGGE period were the result of the interaction between middle and lower latitude systems Besides the influence of tropical summer monsoon, cold air from middle and higher latitudes also played an important role in the rainfalls (2) The three rainfall processes were related with the activities of fronts In each case, the front corresponded to the frontogenetical area and the heavy rainfall occurred near the front or during front passage (3) Computations show that, Q 1 and Q 2 contributed significantly to these rainfall processes of the area of South China, and the convective condensation heating caused by columns convection also played an important role in the rainfalls (4) Heavy rainfalls in South China are associated closely with monsoon circulations During pre-rainy season in 1979, the South China Sea monsoon pushed northwards three times, three rainfall processes had a direct relationship with these activities (5) The moisture source areas of these rainfall processes are analyzed It should be noticed that not only the Bay of Bengal, but also the South China Sea and the West Pacific are important moisture source areas (6) The analysis of the cloud systems indicates that the meso-scale convective cloud clusters provide very favorable conditions to the occurrence of heavy rainfalls