上海城市湿岛与城区雾

THE URBAN MOISTURE ISLAND AND URBAN FOG OF SHANGHAI

本文根据1984年上海城区11个气象站和郊区10个气象站的观测记录和天气图,分析上海城乡水汽压的差异及其与城区雾的关系,发现在气团雾出现前,上海在20时和02时常出现三种城市湿岛,即凝露湿岛、结霜湿岛和雨天湿岛(含雨中湿岛和雨后湿岛两型)。在辐射雾和平流辐射雾(主要出现在秋冬季节)中还有雾天城市湿岛。以上各类湿岛的形成都伴有城市热岛的存在。本文用大量观测事实论证了以上几种城市湿岛的存在及其形成过程,并指出城市湿岛的出现可以作为城市辐射雾、平流辐射雾和平流雾的先兆。

By making use of the simultaneous observational meteorological data in 1984 in Shanghai urban and its suburbs,we discussed the formation of urban moisture island and its relationshipwith urban fog.Three major conclutions are as follows:(1)There are four types of urban moisture island according to their formation:a)with lessdew deposits in the nighttime,b)with less frost deposits in the nighttime,c)more water evapora-tion in or after the rain,d)more water evaporation in the fog time.All the above processes are ac-companied by the urban heat island.(2)The urban moisture island is a very good indication of radiation fog and advection radia-tion fog,but there is little relationship with frontal fog.3)During the radiation fog and advection radiation fog period of autumn or winter,therealways exists an urban moisture island.