1998~2013年青藏高原切变线活动特征统计分析

Statistical Analysis of Shear Line in Qinghai-Xizang Plateau Activity Characteristics from 1998 to 2013

摘要: 本文运用1998~2013年青藏高原低涡切变线年鉴分析高原切变线的活动特征。结果表明，高原切变线主要生成于高原东部，位于27˚~39˚N，高频中心位于昌都地区西北部。切变线向东移可到达湖南，向北移可到达内蒙古，向南移可到达广西等地。近16年来高原切变线的出现次数和移出次数均成增加趋势，1998~2013年高原切变线共生成571次，移出92次。夏半年高原切变线的活动次数高于冬半年，夏半年主要位于8月份，冬半年主要位于4月份，东部横切变线为主。93.8%的高原切变线的生命史在48 h内。影响高原切变线移出的主要系统有西风槽、青藏高压、西藏高压、副热带高压。早期青藏高原西部测站稀少，统计时选取的资料和样本长度以及对于高原切变线的定义标准不同是导致统计结果存在差异的主要原因。

Abstract: This paper analyzes the activity characteristics of the Plateau shear lines with The Tibetan Plateau Vortex and Shear Line Yearbook from 1998 to 2013. The results show that Tibetan Plateau shear lines mainly generated at eastern plateau and located at 27˚ - 39˚N. The plateau shear line mainly occurred at the Northwest of Qamdo. The shear line can reach Hunan when moving eastwards, reach Guangxi when moving southwards and can reach Inner Mongolia when moving northwards. The occurrence and moving out times of plateau shear lines have increased during the past 16 years. The total number of Plateau shear lines is 571 during 1998-2013, moving out 92 times. The activities of plateau shear lines summer-half years more than winter-half years. The summer half- years plateau shear lines mostly appear in August and winter half-years appear in April. Quasi- longitudinal eastern shear lines are majority. 93.8% of the shear lines lifetime is within 48 h. The main weather systems influencing the moving out of plateau shear lines are west wind trough, Tibet high pressure and subtropical high pressure. The main causes leading the differences between plateau shear lines statistical results are the length of selected data and sample, the scarcity of station in western Qinghai-Xizang Plateau and the different definition standard of plateau shear lines.