Characteristics of Frontal Fog in Eastern Yunnan-Guizhou Plateau and the Analysis of Meteorological Impact Factors
Based on the conventional meteorological data from 84 national observation stations in Guizhou Province from 1984 to 2013,the spatio-temporal distribution feature of quasi-stationary frontal fog and its relations with meteorological impact factors are analyzed.The results suggest that:(1)The spatial distribution of quasi-stationary frontal fog is characterized by a high frequency in the west and low frequency in the east of Guizhou.This is closely related to the position and strength of the Yunnan-Guizhou quasi-stationary front and the topography of"high in the west and low in the east"in Guizhou.Seventy-three percent of the frontal fog appears in areas with an altitude of 800-1500 m above sea level.(2)Overall,the annual variation of quasi-stationary frontal fog shows a slowly decreasing trend in Guizhou with a rate of 0.39 days per decade.The central and western part of Guizhou has a decreasing trend of frontal fog days,which is associated with the rise in temperature and the decline in humidity.The quasi-stationary frontal fog mainly occurs in late autumn to early spring,mostly in winter.Frontal fog occurs mostly from night to morning,but its diurnal variation is not obvious.(3)Under the background of Yunnan-Guizhou quasi-stationary front,temperature is 2-6 ℃ with diurnal range being 2-4 ℃.When the 24 h surface pressure and temperature vary in the ranges of-2 to 2 hPa and-2 to 2 ℃,the frequency of frontal fog is the highest.This indicates that stable pressure and temperature have positive values to frontal fog events,but the sharp rise or drop in temperature is not favorable for the formation of frontal fog.When frontal fog occurs the surface wind speed is less than 4 m/s,the wind mainly tends to be calm wind,easterly wind or north wind,followed by southerly wind.In addition,frontal fog is often accompa-nied by little rainfall.
万方数据
维普
