西南季风与登陆台风耦合的暴雨增幅诊断及其数值模拟

摘要

The amplifying of the torrential rainfall of the landing Tropical Storm Bilis（0604） and moisture budget around the typhoon vortex are studied with the dataset of CMA-STI Tropical Cyclone Optimal Tracks,the NCEP/NCAR reanalysis data and the intensive surface observations.Results show that the southwest monsoon provides abundant water vapor for torrential rainfall during the landfall of Bilis,and has important influence on the long time maintenance and torrential rainfall increament of the landing typhoon.The rainfall of Bilis after landfall is simulated by WRF（weather research and forecasting） model,showing that the model can preferably simulate the rainfall intensity and torrential rain area.The simulated path is mainly coincident with the observed path,although there is some difference between them.Rainfall is significantly increased on the south side of the typhoon centre at the onset of the monsoon surge.Results of the sensitive experiments show that the typhoon rainfall intensity is closely associated with the moisture transport,and the decrease of water vapor can remarkably weaken the rainfall,indicating that the moisture transport of southwest monsoon plays an important role in the torrential rainfall of landing typhoon.%以登陆内陆后维持时间长、暴雨增幅的热带气旋＂碧利斯＂（0604）为研究对象,利用＂CMA-STI＂热带气旋最佳路径数据集、NCEP/NCAR再分析资料及地面加密观测资料,讨论了西南季风与登陆台风耦合的暴雨增幅,分析了台风涡旋周围的水汽收支特征,发现净西风、净南风输送为暴雨提供了充足的水汽,在＂碧利斯＂登陆大陆减弱西行的过程中,西南季风对登陆台风的维持和暴雨增幅有重要影响。利用WRF（weather research and forecasting）模式模拟＂碧利斯＂登陆后的降水表明,该模式能够较好地模拟降水强度和暴雨落区,模拟路径与台风实际路径走向大体一致,但存在一定偏差;季风涌爆发时,台风中心南侧降水出现明显增幅。敏感性试验结果表明,降水强度对水汽输送大小较敏感,水汽输送减弱致使降水强度明显减弱,可见西南季风的水汽输送对暴雨的影响至关重要。