广西大范围暴雨期间孟加拉湾强对流演变及东移特征

分析1980~2002年主汛期(5~7月)广西锋面型大范围暴雨期间孟加拉湾对流云团演变及与之相应高低空环流变化,结果表明:孟加拉湾强对流在广西暴雨发生前3天发展最为旺盛,受孟加拉湾低槽引导,对流云团爬上中南半岛进入广西,当其与高原东移的云团相结合时再次发展,造成广西大范围暴雨。分析200 hPa高度场和流场结果表明:当广西暴雨发生时,孟加拉湾、中南半岛及广西受200 hPa南亚高压控制。分析850 hPa水汽通量矢量场结果表明:广西锋面型暴雨发生时,从孟加拉湾到广西上空有一西南气流的水汽输送带,广西暴雨水汽主要来源于孟加拉湾。

Evolution and Eastward Movement Characteristics of Convective Cloud Clusters over Bengal Bay during Heavy Rains in Guangxi

An analysis of the convection cloud cluster variation over the Bengal Bay and the features of circulation at both high-and low-level atmosphere during heavy rain processes in Guangxi occurred from May to July,1980 to 2002 is made.The results shows that convective cloud clusters on the Bengal Bay develop most strongly when there occurs heavy rainfall over Guangxi three days ago.Leading by the 500 hPa Bengal Bay though,the Bengal Bay convective cloud clusters climb up the Indo-China Peninsula and come into Guangxi.When the Bengal Bay convective cloud clusters join the convective cloud clusters moved from the Tibetan Plateau,the clusters develop strongly again,then resulting in heavy rainfall around Guangxi.Analysis of the height and wind flow pattern at 200 hPa shows that the Bengal Bay,the Indo-China peninsula,and Guangxi are under the control of the South-Asia High during heavy rainfall over Guangxi.Analysis of the distribution of the vapor flux vectors at 850 hPa shows that there is a water vapor transmitting belt from the Bengal Bay to Guangxi,and the Bengal Bay is the vapor sources of heavy rainfall over Guangxi.