南京冬季平流雾的生消机制及边界层结构观测分析  

An Observational Study on Physical Mechanism and Boundary Layer Structure of Winter Advection Fog in Nanjing

作　　者：陆春松[1] 牛生杰[1] 杨军[1] 王巍巍[1] 

机构地区：[1]南京信息工程大学大气物理与大气环境重点实验室,江苏南京210044

出　　处：《南京气象学院学报》2008年第4期520-529,共10页Journal of Nanjing Institute of Meteorology

基　　金：国家自然科学基金资助项目(40775012);江苏省高校自然科学重大基础研究项目(06KJA17021);江苏省自然科学基金重点项目(BK2007727)

摘　　要：利用系留飞艇边界层要素探测系统等设备,对2006年12月24—27日发生在南京地区的雾日边界层结构进行了综合探测,深入研究了这次平流雾的生消机制及边界层结构。结果表明:此次雾属于比较典型的平流雾,生成和维持主要决定于暖湿气流和系统性下沉运动,消散主要是干冷空气南下造成的;雾顶下降阶段出现了双层结构,中层逆温是逆温主层,属于下沉逆温及平流逆温,主逆温层强中心始终位于雾顶附近或处于雾顶之下;风速随高度呈现多峰分布,中层急流与强度较弱的中上层和上层急流合并后,又与下层急流出现了一强一弱的波动;在风速较小时,风场趋于均匀化;雾消散时,低层风场趋于线性化;雾主要的水汽来源是暖湿气流;比湿场与风场有较好的时空分布对应性,主逆温层强中心也是逆湿强中心,风场与温度场共同主导了比湿场的时空分布。A comprehensive observation of boundary layer structure was carded out at Pancheng town in the north suburb of Nanjing during fog days between 24th and 27th December,2006 ,using a DigiCORA Ⅲ system for boundary layer elements sounding and an Envirostation TM for surface element observation. The physical mechanism and boundary layer structures of the advection fog are studied thoroughly, and the results are as follows. The formation and maintenance of the relatively typical advection fog was mainly determined by the warm/wet airflow and the systematical sinking motion, and the invasion of dry/cold air resulted in the dissipation of the fog principally. Besides, the fog two-layer structure appeared during the descending period of fog top. The middle temperature inversion, belonging to the subsidence inversion and advection inversion,was a primary inversion,and its intensity center was near or under the fog top. There were several speed maximum values of wind in the vertical. The jets in the middle layer and in the lower layer exhibited strong and weak alternation after the coalescence of the middle layer jet and the weaker ones in the middle-upper and upper layers. While the speed was low, the wind field approached homogenous, and during the period of dissipation, the wind field of the lower layer showed a linear distribution of wind speed with height. The moisture source of the fog was mainly from the warm/wet air flow. There was a good spatial-temporal distribution correspondence between moisture and wind fields, and the intensity center of the main temperature inversion was also the intensity center of the moisture inversion, so that the spatial-temporal distribution of the moisture was mainly determined by both the wind and temperature fields.

关 键 词：平流雾 暖湿气流 边界层结构 

分 类 号：P426.4[天文地球—大气科学及气象学]