摘要
利用1998年Micaps历史天气图、1998年第二次青藏高原科学试验资料和NCEP/NCAR 1°×1°分辨率的再分析资料,对该年夏季两例移出与未移出高原的低涡活动过程及特征进行了对比分析,结果表明,移出与未移出高原低涡的低涡结构特征差异显著:(1)移出高原低涡,低涡环流呈圆形,厚度有3000 m左右,降水区呈环状分布;未移出高原低涡,低涡环流呈椭圆形,厚度为1500 m左右,降水区在低涡的南、西南方。(2)移出高原低涡,低涡区内绝大部分为上升运动区,并且强度在加强、区域扩大;未移出低涡,涡区内上升运动在减弱,上升运动区在缩小。(3)移出高原低涡,涡区内斜压性强,比未移出的大近一倍。(4)移出高原低涡,涡区内500 hPa有高位涡沿东北方向向上输送位涡平流,未移出高原低涡的有次高位涡沿东南方向向下输送位涡平流。(5)移出高原低涡是下层‘正涡度、暖区’、上层‘负涡度、冷区’;未移出高原低涡是下层‘正涡度、冷区’、中层‘负涡度、弱暖区’、上层‘正涡度、冷区’。
Using the historical Micaps weather charts,the Tibetan Plateau Science Experiment（TIPEX） data in 1998 and NCEP/NCAR 1°×1° reanalysis data and analyzing the condition of two Tibetan Plateau vortexes moving out of the Plateau and keeping within the Plateau in 1998,the Plateau vortex intensity,thickness,rainfall characteristic,wind symmetry,vertical movement,baroclinicity,potential vorticity,latitudinal cross-section of temperature and vorticity are compared of Plateau vortex moving out and not moving out of the Plateau.The marked structure difference of the moving out and not moving out of the Plateau vortex are as follows：（1） The vortex circulation is circular shape of the moving out of the Plateau vortex,with altitude about 3000 m and accompanying with circular rainfall area distribution.The vortex circulation is circular elliptical shape of the not moving out of the Plateau vortex,with altitude about 1500 m and accompanying with rainfall distribution in south to southwest region of the vortex.（2） The most of area is ascending movement,is being stronger and with expanding area of the moving out of the Plateau vortex.The ascending movement is being weaker with shrunken area of the not moving out of the Plateau vortex.（3） The baroclinicity of the moving out of the Plateau vortex is stronger in not moving out of the ones,with value about two times than the later one.（4） There is high potential vorticity flow to northeast and upward direction on 500 hPa in moving out of the Plateau vortex area and with flow to southeast and downwards direction in not moving out of the Platea vortex.（5） There are positive vorticity,warm area in under level and negative vorticity,cold area in upper level of the moving out of the Plateau vortex.There are positive vorticity,cold area in under level,negative vorticity,weak cold area in middle level and positive vorticity,cold area of the not moving out of the Plateau vortex.All these enriched understanding of easterly movements of the Plateau vortex characteristics and offers scientific basis to the flood and storm rainfall caused by Plateau vortex moving out of the Plateau.
出处
《高原气象》
CSCD
北大核心
2010年第6期1357-1368,共12页
Plateau Meteorology
基金
国家自然科学基金项目(40475020)
国家科技基础性工作专项项目(2006FY220300)共同资助
关键词
青藏高原低涡
移出与未移出的高原涡
位涡
温度
Tibetan Plateau vortex
Plateau vortexes moving out of the Plateau or not
Potential vorticity
Temperature
