2001年1月滇黔准静止锋在演变过程中的结构及大气环流特征分析

ANALYSIS OF ATMOSPHERIC CIRCULATION AND STRUCTURE OF YUNNAN-GUIZHOU QUASI-STATIONARY FRONT DURING ITS EVOLUTION

利用地面常规观测资料和NCEP/NCAR再分析资料,分析2001年1月的滇黔准静止锋在演变过程中的温湿结构和大气环流特征。结果表明:滇黔准静止锋表现为湿度锋,其大气环流特征与高原关系密切。青藏高原的抬升作用与Hadley环流偏南导致Ferrel环流的生成、加强对云贵高原的天气有重大的影响。对于I、Ⅱ型静止锋,Hadley环流圈南北跨距小,环流圈下沉支偏南,易与高原南部的上升支一起形成反环流,该反环流可产生较强的雨雪、凝冻的灾害性天气;Ⅲ、IV型静止锋,Hadley环流圈北推,环流圈南北跨距大,此时在青藏高原的南部无反环流存在,云贵地区上升运动较弱,产生的降水与天气也较弱。由于受副高增强的间接影响,Hadley环流在Ⅱ、Ⅲ、IV型静止锋存在明显的双层结构。

Based on general ground observation data and NCEP data, the atmospheric circulation and the structure of Dian-Qian Quasi-stationary Front （named as DQQSF, same hereafter） during Jan. 2001 are studied. The results show that the DQQSF is a front of humidity and its circulation features are highly related to Tibetan Plateau. The weather of Yunnan-Guizhou Plateau is greatly impacted by the emergence of the Ferrel cell, which is resulted from the lifting effect of Tibetan Plateau and the southward anomaly of the Hadley cell. Corresponding to Pattern Ⅰ and Ⅱ Quasi-Stationary Front, the north-south distance of Hadley cell is short and its sinking branch is southward, which helps form counter-circulation with its rising branch at the south plateau. It is the counter -circulation that result in the severe weather such as snow, ice rain etc. In contrast, the Ⅲ and Ⅳ pattern Quasi-Stationary Front occurs with the north Hadley cell with longer north-south distance, and there is no counter-circulation over the south Tibetan plateau. Because of the indirect influence of the strengthening subtropical anticyclone, the Hadley cell shows a two-layer structure corresponding to the quasi-stationary front in Pattern Ⅱ, Ⅲ and Ⅳ.