三江源地区暴雨的水汽输送源地及路径研究

利用NCAR/NCEP再分析数据,首先分析了2018年7月22-23日(简称"0722")和8月2-3日(简称"0802")三江源地区两次暴雨天气过程的天气形势和水汽输送特征,然后用WRF模型输出数据驱动HYSPLIT模型,定量分析两次暴雨的水汽输送路径及各路径的水汽贡献率。研究表明:两次暴雨的主要影响系统均为三江源东部地区形成的低涡和切变线,低涡系统的演变和进退对暴雨的强度和落区有很大影响;HYSPLIT模型使用WRF模型输出的高分辨率数据作为初始场,模拟效果良好;两次暴雨的主要水汽均来源于西南和东南路径。西南路径的水汽来自孟加拉湾,通过雅鲁藏布江大峡谷水汽输送通道输送至暴雨区。东南路径的水汽来自于东海和南海,从广东和湖南等地向西北传输至暴雨区;"0722"暴雨中还存在西北路径的水汽输送,此路径的水汽输送贡献率较小。

Study on Water Vapor Transport Source and Path of Rainstorm in Sanjiangyuan Area

Based on the NCAR/NCEP reanalysis data,the weather situation and water vapor transport characteristics of two typical rainstorm weather processes in Sanjiangyuan on July 22-23("0722")and August 2-3("0802")were analyzed firstly.Then,the WRF model was used to output data for driving the HYSPLIT model to quantitatively analyzing the water vapor transport of the two storms.The results show:(1)The main influence systems of the two rainstorms are the vortex and shear lines formed in the eastern region of Sanjiangyuan and the evolution and advance and retreat of the vortex system has great influence on the intensity and fall area of the rainstorms.(2)The HYSPLIT model uses the high-resolution data output from the WRF model as the initial field and the simulation works well.(3)There are three main moisture transport routes for the“0722”rainstorm:10 days before the rainstorm,the gas blocks in the northwest path were located in the western region of Xinjiang and entered the Sanjiangyuan via the northern Qinghai-Xizang Plateau,the moisture transport contribution rate is 16%;The air parcels in the southwest path originate from the north of the Bay of Bengal and are transported to Sanjiangyuan through the water vapor transport channel of the Yarlung Zangbo River Grand Canyon,with the water vapor transport contribution rate is 41.5%;Water vapor in the southwest path existed in Guangxi 10 days ago and transported to the rainstorm area through Sichuan and other places,with water vapor transport contribution rate acbeing 42.5%.(4)The water vapor of the"0802"rainstorm is mainly transported to the Sanjiangyuan area via four routes:one route is southwest,and the water vapor of the Bay of Bengal is transported to the rainstorm area through the Yarlung Zangbo River Grand Canyon,the water vapor transport contribution rate is 28%.The remaining three are southeast routes:ten days ago,the main source of water vapor appeared in Guizhou and Hunan and is transported to Sanjiangyuan in the northwest direction,the contribution rate of water vapor transportation of the three routes being 23%,23% and 26%,respectively.(5)In general,the main water vapors for the two rainstorms come from the southwest and southeast paths.The water vapors in the southwest path come from the Bay of Bengal and are transported to the rainstorm area through the Water vapor transport channel of the Yarlung Zangbo River Grand Canyon.The water vapors along the southeast path are transferred-toward the northwest from Guangdong and Hunan to the rainstorm area.For the rainstorm of"0722",there are also water vapors transport along the northwest path,which has a small contribution rate.