一次副高外围雨雾的诊断分析

Diagnostic Analysis of a Peripheral Rain and Fog in Subtropical High

应用实测资料和ECMWF、T213模式再分析资料，对2008年7月7—9日由于西太平洋副高的北进南撤，在河北中南部产生的雨雾天气过程进行了诊断分析。分析表明：500hPa我国大陆高度场和温度场均是∏字型结构，对西太平洋副高的进一步西伸和水汽向河北的输送起到了制约作用；河北中南部上暖下冷的气团配置，是造成河北中南部大气稳定的一个原因。对流层弱的气压场和风场，是大气层结稳定的一种表现。500hPa小冷槽的东移，是产生雷暴和短时强降水的触发机制，以及导致西太平洋副高南撤的一个重要因素。地面均压场的建立及近地面辐射冷却为大雾的形成提供了有利的风速和冷却条件。

Based on the conventional data, ECMWF and T213 grid data, the rain and fog occurring as the West Pacific subtropical high moving northward in central and southern of Hebei province duringJuly 7-9 2008 is analyzed. The results show that the characteristics of 500 hPa height field and tempera- ture field are H-shaped structure in China mainland. It plays a restraint effect on the further westward extension of West Pacific subtropical high and the delivery water vapor to Hebei province. The air mass disposition with the up warm and under cold is a reason of the atmospheric stability in central and southern of Hebei province. Weak pressure field and wind field of the troposphere are a manifestation of a stable atmospheric stratification. The little cold trough move eastward of 500 hPa high is the trigger mechanismto produce strong thunderstorms and the short-term precipitation, and it is an important factor leading the West Pacific subtropical high move to south. The established ground uniform pressure field and radiation cooling have provided favorable wind speed and cooling conditions for the formation of dense fog.