摘要
利用NCEP再分析资料、常规观测资料和FY-2E黑体亮温(TBB)资料对2010年7月21-26日一次成熟阶段垂直厚度大于500 h Pa的深厚高原涡的结构和演变特征进行了综合分析,探讨了此次深厚型低涡的发生发展与高层环流的关系。结果表明:(1)深厚型高原涡生成阶段,低涡内辐合弱,下沉运动强,动力辐合作用不是该低涡发展至对流层高层的原因。南亚高压北侧、东侧高空急流的下沉支流将高层高位涡、高动量的空气向下输送,促使该低涡生成、发展。深厚型高原涡的演变与南亚高压联系密切,南亚高压东部脊线北抬,形成"东北-西南"向,其东南侧的东北气流引导深厚型低涡向西移动。(2)浅薄型高原涡500 h Pa上暖心明显,其上为冷性结构。深厚型高原涡在热力结构上分层明显,时空演变较为复杂,低涡在250 h Pa上与南压高压具有相同的暖性结构,250 h Pa以下为冷性结构,冷性结构的转变过程在不同高度上存在差异。(3)对比不同阶段深厚型高原涡与浅薄型高原涡的动力差异发现,低涡形成前期,深厚型高原涡有强辐合和上升运动,而浅薄型高原涡辐合较弱,以下沉运动为主;在消散期,深厚型高原涡主要减弱因子是水平涡度平流,而垂直涡度转换成水平涡度是造成浅薄型高原涡垂直涡度下降的主要原因。
A present understanding of Plateau Vortex （PV） is regarded as a shallow vortex. However, some studies have pointed out that PV is not always a shallow system. A case of PV with a vertical thickness greater than 500 hPa were analyzed using the NCAR/NCEP reanalysis data, the conventional observations as well as the TBB data from FY-2E, and we discussed the relationship between the deep plateau vortex and the upper circula- tion. The results show ： （ 1 ） In the developing stage, the convergence of vortex is weak while the downdrafts are strong, convergence is not the reason for the development of the deep plateau vortex which extended to the upper troposphere. The downdrafts of the high potential vorticity and high momentum form the upper air transported by the upper-level jet stream which in the north and east of the South Asian High （SAH） led to the generation and development of vortex. The evolution of the deep plateau vortex is related to SAH. Therefore, the eastern ridge of the SAH moved to the north and a ＂northeast-southwest＂ pattern was formed, the northeast flow of southeast SAH led the deep plateau vortex to the west. （2） The shallow PV has a warm character in thermal structure with a warm core at 500 hPa. The deep vortex has stratification in thermal structure and complex variety in time and space, Besides, it has a warmer structure as same as the SAH at 250 hPa and a colder structure below 250 hPa, the changes of the cold part of the vortex vary from height in different stages. （3） Comparing the dynamic char- acters between deep and shallow vortices in various stages, we found the deep PV has a stronger convergence and ascending motion in the early than the shallow PV which dominated by the subsidence movement. During the dis- sipation stage, horizontal vorticity advection is the main factor which causes the deep PV become weaker. On the other hand, the vertical vorticity conversion to the horizontal is the main reason for the decrease of the shallow PV.
作者
杨颖璨
李跃清
陈永仁
YANG Yingcan;LI Yueqin;CHEN Yongren(Chinese Academy of Meteorological Sciences, Beijing 100081, China;Institute of Plateau Meteorology, China Meterological Administration Chengdu 610072, Sichuan, China;Sichuan Meteorological Observatory＇, Chengdu 610072, Sichuan, China)
出处
《高原气象》
CSCD
北大核心
2018年第3期702-720,共19页
Plateau Meteorology
基金
国家自然科学基金重点项目(91337215)
国家自然科学基金面上项目(41275051)
四川省应用基础研究计划重点项目(2016JY0046)
关键词
垂直厚度
高原涡
高层环流
Vertical thickness
Plateau Vortex
upper circulation
