孟加拉湾对流对广西秋季暴雨影响分析

利用综合观测数据1 °×1 °FNL和2.5 °×2.5 °NCEP再分析资料、以及卫星云顶黑体辐射温度资料（TBB），对2015年11月广西出现的三次暴雨过程（8日、11—12日和20日）的850 hPa水汽通量散度及水汽输送特征进行了对比分析。8日和20日暴雨的低层水汽主要来自南海，11—12日连续暴雨的水汽来自南海和孟加拉湾。暴雨前后TBB的分析表明，在暴雨发生前2~3 d，孟加拉湾对流发展到最强，孟加拉湾对流对广西秋季暴雨具有前兆信号特征。暴雨前后TBB时空剖面表明，暴雨发生前孟加拉湾对流有向广西波动传播的特征。模式敏感性实验显示，当关闭孟加拉湾对流2~3 d后，广西48 h累计雨量减小。 

ANALYSIS OF THE IMPACT OF THE CONVECTION OVER THE BAY OF BENGAL TO AUTUMN HEAVY RAIN IN GUANGXI

Based on conventional observation data, the 1 °×1 ° FNL and 2.5 °×2.5 ° NCEP reanalysis data and the black body temperature data at the top of the cloud (TBB), a comparative analysis was conducted of the 850 hPa water vapor divergence and vapor fluxes of three heavy rainfall events (on 8, 11—12 and 20 November) in Guangxi in 2015. On 8 and 20 November low-level water vapor was transported from the South China Sea, while water vapor was not only transported from the South China Sea but also from the Bay of Bengal during 11—12 November 2015. The analysis of the TBB data before and after the occurrence of heavy rains showed that 2~3 d before the heavy rainfall, the convection over the Bay of Bengal developed vigorously. The convection over the Bay of Bengal is a precursory signal to the autumn heavy rain in Guangxi. TBB time-space profiles before and after the heavy rainfall showed that the convection of the Bay of Bengal spread in the form of waves from the Bay of Bengal to Guangxi before the autumn heavy rainfall. Model sensitivity experiments showed that 2~3 d after the heat source over the Bay of Bengal was shut off, 24-hour cumulative precipitation was reduced.