台风“凤凰”和“诺瑞丝”路径与降水分布对比分析

Analysis of Typhoons "Fung-Wong" and "Norris" with Similar Tracks and Different Rainfall Patterns

台风"凤凰"(0808)和"诺瑞丝"(8012)路径相似,但降水分布不同,"凤凰"暴雨分布在路径左右两侧,而"诺瑞丝"暴雨分布在路径左侧。文章从湿位涡和垂直风切变角度对这两个路径相似台风暴雨进行了诊断分析。结果表明:无论是"凤凰",还是"诺瑞丝"台风暴雨与湿位涡和垂直风切变都有较一致对应关系,强降水位于垂直风切变矢量左侧,垂直风切变矢量与移动路径呈不同夹角时,强降水分布在移动路径不同方位。湿位涡正压项(MPV1)负值区和斜压项(MPV2)正值区相叠加对应强降水落区,而且叠加区内MPV2越大,降水强度也越强。因此,在实际台风预报中,可以结合湿位涡和垂直风切变综合分析来提高预测强降水落区准确性。

The Tropical Cyclones （TC）with similar tracks generally have similar rainstorm patterns,but Typhoons Fung-Wong （0808） and Norris （8012） are exceptions,which have similar tracks but different precipitation distribution. The rainstorms of Fung-Wong distributed in two sides of the track,but those of Norris distributed in the left side of its track. The typhoon rainstorms are diagnosed and analyzed by means of moist potential vorticity （MPV） and vertical wind shear analysis. It is found that,regardless of Fung-Wong or Norris,MPV and vertical wind shear of both have the consistent corresponding relationship with typhoon rainstorms. The strong precipitation occurred on the vertical wind shear left side,and when vertical wind shear vectors and TC track angled differently,there occurred different heavy rainfall distributions along the TC track. The overlapped areas of negative MPV1 and positive MPV2 are usually severe rainfall areas,and the greater the positive value of MPV2 in the overlapped area,the stronger the intensity of rainstorm. Therefore,in the typhoon forecasting practice,the accuracy of rainfall location forecast can be improved by using the comprehensive analysis of MPV and vertical wind shear.