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移出高原后长生命史高原低涡在不同移动路径下的大尺度环流特征及差异 预览

Comparison Analysis of Circulation Features Moving Tracks of Long-Life-Cycle Plateau Moving out of the Plateau of Different Vortexes
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摘要 利用NECP再分析资料及高空观测资料,对2000--2010年移出青藏高原后生命史长达3天或以上的高原低涡进行统计,并根据移动路径的不同将其分为东移、东北移和东南移三类,统计结果表明:在不同时间段,不同移动路径的长生命史高原低涡具有不同的活跃度,盛夏7月,东移个例远远多于东北移和东南移个例,东南移个例多于东北移个例;而在夏末8月,东南移个例则远多于东北移和东移个例。选取不同移动路径的个例,进行对流层中上层环流背景特征分析,指出其500hPa环流形势,温度平流及200hPa环流形势的共同特征和差异。分析结果表明:500hPa环流形势,副热带高压的位置、走向分布对长生命史高原低涡的移动路径有显著影响。东移、东北移、东南移三种路径,副热带高压依次减弱。印缅地区,东南移路径为季风低压,而东移和东北移路径则为季风槽或印缅槽,即东南移路径25。N以南具有相对较低的位势高度,有利于高原低涡的向南移动;200hPa环流,东移、东北移、东南移三种路径,南亚高压1252dagpm东伸脊点依次偏西。东移路径,南亚高压东伸脊点的明显偏东,使得高原低涡移出高原后受一致西风引导气流的影响,而对于东南移个例,相对北抬的南亚高压前及相对较深的110。E槽后的西北气流对高原低涡的东南移具有一定的引导作用。温度平流带随时间的走向与不同路径的移动方向有着较好的对应关系。移出高原后的长生命史高原低涡基本在平均冷平流带中移动,东南移的高原低涡个例具有相对较强的冷空气活动,使得高原低涡能够向相对较暖的南方移动。 Using the upper-air observation data and the corresponding daily average NCEP reanalysis data, this paper first statistically analyzed the plateau vortexes which could live 3 days or longer after moving out of Tibetan Plateau in summer from 2000 to 2010. According to their different moving track, the vortexes were divided into three groups which are moving eastward, northeastward and southeastward. The results show that in July long-life-cycle vortexes moving out of the plateau move eastward far more than northeastward and southeastward, and the vortexes moving southeastward are more than those moving northeastward. However, in August, the vortexes moving southeastward are far more than those moving northeastward and eastward. Then by selecting the cases of different moving tracks, we analyzed the gen- eral circulation in the mid-upper troposphere, pointing out the common features and differences of the gen- eral circulation and temperature advection at 500 hPa and the circulation at 200 hPa. The findings indicate that the position and shape of West Pacific subtropical high influence the long-life-cycle plateau vortex moving out of the plateau at 500 hPa significantly, and the strength of the subtropical high decreases in the order of the tracks moving eastward, northeastward and southeastward. The southeastward track over the Indian-Burma Region is affected by monsoon depression while the eastward and northeastward tracks are affected by the Indian monsoon trough, namely to south of 25~N of the southeastward track there is a rela- tively lower geopotential height which is favorable for the plateau vortex to move southward. Under the 200 hPa circulation background, the eastern end of the 1252 dagpm South Asia high is by west in the order of eastward, northeastward and southeastward tracks. For the eastward track cases, the eastern end of South Asia high is obviously by east, causing the westerly flow to guide the plateau vortex to move east- ward. And for the southeastward track cases, the northern boundary of th
作者 师锐 何光碧 SHI Rui HE Guangbi (1 Chengdu Institute of Plateau Meteorology, CMA, Chengdu 610072 2 Siehuan Meteorological Observatory, Chengdu 610072 3 Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Siehuan, Chengdu 610072)
出处 《气象》 CSCD 北大核心 2018年第2期213-221,共9页 Meteorological Monthly
关键词 长生命史高原低涡 大尺度环流 温度平流 南亚高压 long-life-cycle plateau vortex, large-scale circulation, temperature advection, South Asia high
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