摘要
一般认为相似路径台风的影响大致相似,但实际上相似路径台风的风雨分布尤其是暴雨分布往往有很大差异,因此,对相似路径热带气旋"海棠"(0505)和"碧利斯"(0604)暴雨成因的对比分析有助于加强台风暴雨发生机制的认识和预报。"海棠"(0505)和"碧利斯"(0604)逐日降水分布对比分析表明,两者登陆前降水分布类似,而登陆后降水分布差异比较大。利用NCEP/GFS1°×1°分析资料对热带气旋登陆前后天气形势、水汽通量和水汽通量散度进行诊断分析,结果表明:"海棠"(0505)和"碧利斯"(0604)登陆前引起浙闽沿海地区大降水主要是热带气旋外围偏东气流和地形共同影响下形成。"海棠"登陆后,维持在浙江东部沿海东南风急流不断输送水汽到"海棠"倒槽内引起浙东南沿海强降水,深入内陆后,降水主要由"海棠"自身环流携带的水汽辐合引起的,降水比沿海地区明显减弱;而"碧利斯"登陆后,有明显的南海季风环流输送水汽并入热带气旋南侧环流,在其南侧形成偏南风急流,使南侧水汽输送得到明显加强,造成"碧利斯"南侧水汽通量辐合,北侧水汽通量辐散,南侧降水比北侧降水强很多;深入内陆后,"碧利斯"环流仍维持并引导北方槽后弱冷空气渗透到其西南侧,使南侧降水进一步增幅。本文还探讨了包括热带气旋外核在内区域平均垂直风切变和热带气旋强降水落区的关系,结果表明:"海棠"和"碧丽斯"大暴雨落区均对应于暴雨区区域平均垂直风切矢量左侧水汽通量散度负值区。"海棠"垂直风切变矢量平行于移动路径并指向移动路径后方是造成"海棠"强降水分布在其移动路径右侧的重要原因,"碧利斯"垂直风切变矢量平行于移动路径并指向移动路径前方是造成"碧利斯"强降水分布在其移动路径左侧的重要原因。因此,利用垂直风切结合水汽输送条件可以作热带气旋大暴雨落区预报可能是一种比较有效的方法。
It is generally thought that the influence of similar track typhoon is approximately similar, but in fact their wind and rain distribution, especially rainstorm distribution, are often very different. Therefore, a contrastive analysis of rainstorm by tropical cyclones ＂Haitang＂ （0505） and ＂Bilis＂ （0604）, which are with similar track, is designed to help understand the mechanism for TC rainstorm and improve forecasting skills. The daily rainfall of the tropical cyclones（TCs） ＂Haitang＂（0505） and ＂Bilis＂ （0604） are diagnosed and compared. The result indicates that two TCs have similar precipitation distribution before landfall but different precipitation characters after landfall. Using NCEP/GFS analysis data, the synoptic situation is analyzed, and the water vapor transportation is discussed with the calculated water vapor flux and its divergence. The results show that the heavy rainfall in Zhejiang and Fujian province associated with ＂Haitang＂（0505） and ＂Bilis＂（0604） before landfall is resulted jointly from periphery easterly wind of the tropical cyclone and terrain. But after landfall and moving far inland of the storm, the precipitation of ＂Haitang＂ is caused by water vapor convergence carded by its own circulation and it is much weaker than the coastal area. One of important reasons leading to heavy rainstorm in southeast Zhejiang is that a southeast jet stream maintains over the southeast coast of Zhejiang. In contrast, South China Sea monsoon circulation transports much water vapor to ＂Bilis＂, when a water-vapor transfer belt south of the tropical cyclone significantly strengthened, enabling the transfer to strengthen. Then, it causes water vapor flux to converge on the south side of ＂Bilis＂ and diverge on the north side. Precipitation is much stronger on the south side than the north side. After ＂Bilis＂ passes into the interior, the cold air guided by a north trough goes into the tropical cyclone and enhances the precipitation remarkably. In summary, combining vertical wind shear with water vapor transportation is a good way to predict rainstorms associated with landing tropical cyclones.
出处
《热带气象学报》
CSCD
北大核心
2009年第1期37-47,共11页
Journal of Tropical Meteorology
基金
温州市科技计划项目(S20080030)
乐清市科技计划项目(2006R003)共同资助
关键词
天气预报
热带气旋
台风暴雨
相似路径
水汽通量
垂直风切
weather forecast
tropical cyclone
typhoon rainstorm
similar tracks
water vapor flux
vertical wind shear
