2012年2月22日江西平流雾过程的环流特征与诊断分析

利用常规气象观测资料和NCEP再分析资料,对江西2012年2月22日的平流雾天气过程进行了诊断分析。结果表明,低层850—925 hPa江南有暖脊发展,且西南气流与等温线交角较大时,暖湿平流的输送为平流雾的形成提供了有利的平流逆温层结和水汽条件。当地面西南倒槽向东北方向发展时,在700—850 hPa西南急流的南侧有辐散下沉气流,925 hPa到近地层有弱辐合上升气流,两支气流的垂直混合有利于水汽聚积在逆温层下而形成雾。平流雾易形成于低层回温最明显且与地面逆温强度最大的时段。

CIRCULATION FEATURE AND DIAGNOSTIC ANALYSIS OF AN ADVECTION FOG EVENT IN JIANGXI

Based on the conventional observation data and NCEP reanalysis data, the synoptic situation fields of the advection fog, occurred on March 22, 2012 in Jiangxi, were analyzed. The results show that a warm ridge developed between 850-925 hPa. The the warm and wet advection transportation to Jiangxi provided inversion and vapor conditions for the advection fog formation. When the ground trough developed towards the northeast, there existed a divergence downdraft at the south side of southwest jet between 700-850 hPa and a weak convergence updraft from 925 hPa to the ground. The vertical mixing of the two air flows was conducive to moisture accumulation to form fog in the inversion layer. Advection fog is easily formed accompanied by the rising of low layer temperature and the intensity of ground temperature inversion.