1979-2016年青藏高原低涡的变化特征研究

摘要

青藏高原低涡(Tibetan Plateau Vortex,TPV)是造成我国暴雨的重要天气系统之一.基于1979-2016年ERA-In-terim逐日再分析资料,通过客观识别方法,对TPV进行筛选,并以部分年份的TPV与《青藏高原低涡切变线年鉴》(以下简称年鉴)中的TPV进行了对比分析.主要得到如下结果:(1)客观识别TPV与年鉴TPV的平均吻合率为66.2%;其频数和中心位势高度与年鉴TPV的呈显著相关.(2)近40 a的TPV频数呈显著增加趋势,年均56.3个,存在准6 a和准10 a周期.(3)TPV中心位势高度呈正态分布,其持续时间呈指数减少趋势,其频数、持续时间和中心位势高度均呈夏强冬弱.(4)33°-36°N,80°-90°E是TPV出现的高频带,其高频轴线位于35°N附近,那曲地区西部和阿里地区北部是其高频中心;西部涡、中部涡和东部涡分别占TPV总数的32.6%、46.0%和21.4%;东移型、准静止型和西移型TPV分别占TPV总数的61.4%、34.3%和4.3%.(5)基于该识别方法建立的TPV数据集,可为进一步开展TPV研究提供重要参考依据.%Tibetan Plateau Vortex(TPV)is one of the major systems that induce heavy rain in China during summer.Based on ERA-Interim daily reanalysis data from 1979 to 2016,we have identified TPVs by using an objective identification method,and compared these TPVs to the TPVs in Tibetan vortex and shear line yearbook(here in after referred to as yearbook)in certain years.The main results are as follow.(1) The average agreement rate between TPVs by objective identification and ones from yearbook was 66.2%,and the frequency and the center geopotential height of both TPVs have a clear correlation.(2)During the past 40 years,the frequency of the TPVs has increased significantly. The annual mean TPV frequency was 56.3,which presents a quasi-six-year and a quasi-ten-year periodic oscillation.(3)The center geopo-tential height of the TPVs has a normal distribution,whose duration decreased exponentially,and the frequency,center height and duration all presented a pattern of strong or long in summer and weak or short in winter.(4)The high TPV frequency area was situated in 33°-36°N and 80°-90°E,whose axis is located around 35°N,with two high TPV frequency centers being in the eastern Nagqu and northern Ngari.The TPVs generated in the western,central and eastern areas accounted for 32.6%,46.0% and 21.4% of total TPVs,respectively.The eastward-moving, quasi-stationary and westward-moving types of TPVs accounted for 61.4%,34.3% and 4.3% of total TPVs,respectively.(5)The TPV dataset established based on the objective identifying method can provide important references for the further research of TPV.