基于多源资料的高原低涡源地研究

Reexamine the Tibetan Plateau Vortices Sources Based on Multiple Resource Datasets

高原低涡是活跃于青藏高原近地面层的中尺度天气系统,是高原最重要的降水天气系统,少部分的低涡移出高原后在下游地区常带来灾害性的强降水天气。“青藏高原低涡切变线年鉴”(简称年鉴)是高原低涡研究的主要参考资料之一,但受到高原西部地区探空观测站点分布不足的影响,年鉴难以监测发源于高原西部的低涡。为了进一步提高对高原低涡源地的科学认识,本研究首先分析了影响高原低涡发生发展的环流在高原东西部地区的差异,结果表明高原西部地区的环流背景更有利于高原低涡形成。再利用2005~2019年暖季(5~9月)风云-2地球静止卫星观测的云迹风和黑体亮温资料对年鉴低涡进行重分析,表明年鉴中大部分的高原低涡可以溯源至高原西部地区。最后分析了在高原西部的3个新探空站(狮泉河、改则和申扎)建立前后年鉴中高原低涡源地的差异,发现增加的探空资料使位于高原西部的低涡源地大幅度增加。综合多源资料的结果,我们认为大多数高原低涡起源于高原西部,年鉴的结论可能源于高原西部的探空站不足的影响。本研究确认了再分析资料在高原低涡研究中的可用性和有效性,强调了卫星观测资料在高原天气系统研究中的重要性和进一步增强高原地区气象观测的迫切性。

The Tibetan Plateau vortex(TPV)is a kind of mesoscale weather system that exists near the surface of the Tibetan Plateau(TP).TPVs are the major precipitation-producing weather system over the TP,and a small portion of the TPVs move off the TP,causing catastrophic heavy rainfall in the downstream areas of the TP.The yearbook of the TPVs edited by the Chengdu Institute of Plateau Meteorology offers important references in the field of TPVs research.The TPV source of the yearbook is dominantly located over the eastern TP,but most TPVs obtained via the reanalysis are generated over the western TP.It is the most significant difference between the TPVs derived from the yearbook and the reanalysis.To clarify the source of TPVs,we first examine the differences in the general circulation between the eastern and western regions of the TP that affect the development of the TPVs and find that the large-scale circulation in the western TP is more favorable to the generation of TPVs.Second,the atmospheric moving vector and blackbody bright temperature derived from the FY-2 geostationary satellites during 2005–2019 are used to reexamine the TPV sources from the yearbook,showing that most TPVs are generated from the western TP.Finally,we checked the difference in the TPV source via the yearbook between the former and later periods of the construction of the three new sounding stations over the western TP,which are Shiquanhe,Gaize,and Shenzha.It shows that the new data significantly increases the proportion of TPVs generated from the western TP.Combining the results obtained from multiple sources,we conclude that most TPVs originate in the western part of the TP,and the conclusion of the yearbook may be misguided because of the insufficient soundings in the western part of the TP.This study confirms the availability and reliability of reanalysis data in the study of TPVs and emphasizes the importance of satellite-based observations in the study of weather systems and the urgency of further enhancing observations over the TP.