台风“温比亚”影响期间山东极端降水过程水汽来源及源区贡献定量分析

Moisture Sources and Quantitative Analysis of Source Contributions of Extreme Precipitation in Shandong Province Affected by Rumbia

利用拉格朗日后向轨迹追踪模式HYSPLIT,结合蒸发—降水诊断法及相关的水汽贡献定量分析法,分析了台风"温比亚"影响期间山东极端强降水的水汽来源及输送特征。结果表明:区域极端强降水的发生与大尺度的水汽输送和辐合密切相关;影响强降水的水汽源地主要有4个,它们分别位于印度洋→孟加拉湾→南海、低纬西太平洋、中纬度西北太平洋和中国东部;源区贡献定量分析表明,低纬西太平洋对极端降水的水汽贡献最大,中纬度西北太平洋次之,印度洋→孟加拉湾→南海与中国东部的贡献相当且均低于中纬度西北太平洋;进一步对比不同源区的水汽输送差异发现,虽然印度洋→孟加拉湾→南海初期摄取的水汽较多,但输送过程中过高的沿途水汽损耗,显著降低了其对极端降水的水汽贡献,尽管中纬度西北太平洋和中国东部地区初期摄取的水汽较少,但两者沿途的水汽损失亦小并且两者摄取的水汽在目标区实际转为降水的比例较高,因此两者最终的水汽贡献不容忽视。

Based on the HYSPLIT model,a Lagrangian particle dispersion model,combined with E-R(evaporation minus precipitation)diagnostics and the related quantitative analysis method of water vapour contribution,the water vapour source and transport characteristics of extreme precipitation in Shandong Province affected by Rumbia(August 2018)are diagnosed.Results indicate that the occurrence of extreme precipitation was related to global water vapour transport and convergence.The water vapour of extreme precipitation mainly came from the regions of the Indian Ocean-Bay of Bengal-South China Sea,the low-latitude western Pacific,the Mid-latitude Northwest Pacific and Eastern China.The low-latitude western Pacific made the largest contribution,followed by the Mid-latitude Northwest Pacific,while the Indian Ocean-Bay of Bengal-South China Sea and Eastern China both contributed similar amounts that were less than those from the Mid-latitude Northwest Pacific.Besides,by comparing with differences of water vapour transport in different source regions,it is found that although the uptake from the region of the Indian Ocean-Bay of Bengal-South China Sea was relatively high,its ultimate contribution to the target precipitation was dramatically reduced due to evaporation in the air parcels.Despite the uptake from the Mid-latitude Northwest Pacific and Eastern China were relatively low.Still,moisture loss in transit was also small,and the released proportion from the former was higher,so their contribution cannot be ignored.