陕西夏季旱涝与欧亚大气环流异常的关系

Relationship Between Summer Flood and Drought in Shaanxi Province and Eurasian Atmospheric Circulation Anomalies

陕西处于青藏高原边坡地带,南北狭长,气候类型多样,地形复杂,生态条件脆弱,旱涝是夏季的主要气象灾害,因此分析其旱涝的成因对该地区防灾减灾具有重要意义。利用陕西78个气象站1961—2018年夏季(6—8月)降水资料、NCEP/NCAR高度场和风场再分析资料、西太平洋副高指数资料,通过相关、合成、多元回归分析方法,研究了陕西夏季旱涝与大气环流异常的关系。结果表明,500 hPa上乌拉尔山阻塞高压和西太平洋副高是影响陕西夏季旱涝的关键因素,当乌拉尔山阻高和西太副高偏强时,陕西夏季降水偏多,反之偏少。200 hPa西风急流位置与陕西夏季降水关系密切,急流偏南时陕西夏季降水偏多,反之偏少。西太平洋副高偏强、偏西时,陕西夏季降水偏多,反之偏少,副高脊线位置主要影响陕西夏季雨带的南北移动。

Shaanxi is located at the edge of the Qinghai-Tibet Plateau,with a narrow and elongated shape,diverse climate types,complex topography and fragile ecological conditions.Drought and flood are the main meteorological disasters in summer,so analyzing the causes of drought and flood in this area is of great significance for disaster prevention and reduction.Based on the precipitation data of 78 meteorological stations in Shaanxi from 1961 to 2018,NCEP/NCAR height and wind fields reanalysis data,and the subtropical Western Pacific Index data,this paper studies the relationship between the abnormal atmospheric circulation and the drought and flood in summer in Shaanxi through correlation,synthesis,and multiple regression analysis.The results show that the blocking high over the Ural Mountains and the subtropical Western Pacific are the key factors affecting the drought and flood in summer in Shaanxi.When the blocking high over the Ural Mountains and the subtropical Western Pacific are strong,the precipitation during summer in Shaanxi is abundant,while it is scarce otherwise.The position of the westerly jet at 200 hPa is closely related to the precipitation in summer in Shaanxi.When the jet is located to the south,the precipitation in summer in Shaanxi is abundant,while it is scarce otherwise.When the subtropical high in the Western Pacific is strong and located to the west,the precipitation in summer in Shaanxi is abundant,while it is scarce otherwise.The location of the subtropical high frontal mainly affects the north-south movement of the rain band in summer in Shaanxi.