热带风暴Bilis(2006)登陆期间一波非对称降水分布成因的探讨

Causes of wave number-1 asymmetric rainfall distribution of tropical storm Bilis(2006) during its landfall

利用中尺度数值模式WRF-ARW对Bilis(2006)进行数值模拟,并进行地形和下垫面因素2个敏感性试验,诊断分析Bilis(2006)登陆期间一波非对称降水结构形成的动力因子。综合分析3个试验,结果表明环境垂直风切变对Bilis(2006)一波非对称降水结构形成的影响显著大于地形、登陆过程下垫面属性的改变和风暴移动速度的影响,冷空气的侵入对降水形成也有重要贡献。垂直切变的作用使顺切变左侧形成强降水,冷空气的作用与垂直切变的作用相互配合可能是顺切变方向和顺切变方向右侧强降水的主要成因。

The mesoscale numerical model WRF-ARW was used to simulate iment and two sensitivity experiments in which the effects of terrain and Bilis （2006） in a control experunderlying surface factor were studied. The dynamic factors to form wave number-1 asymmetric rainfall structure of Bilis （2006） during its landfall were diagnosed. The results of the three experiments were analyzed comprehensively to show that the influence of environmental vertical wind shear on wave number-1 asymmetric rainfall structure of Bilis was significantly more important than the terrain, change of underlying surface properties during landfall, and storm speeds. On the other hand, the intrusion of cold air also played an important role in forming local rainfall. Heavy rainfall formed in downshear left quadrant under the effects of vertical wind shear, while heavy precipitation appeared in downshear direction and downshear right quadrants due to vertical shear and the intrusion of modest cold air.