Analysis of Heavy Fog SpatioTemporal Distribution and Meteorological Element Evolution in Guizhou from 2016 to 2017
The hourly observation data of automatic station in Guizhou Province from 2016 to 2017 were used to analyze the spatiotemporal distribution characteristics of heavy fog. Meanwhile, 31 days of front fog and 17 days of radiation fog were screened out via analyzing the synoptic data, and the evolution characteristics of meteorological elements such as wind, temperature and humidity were compared and analyzed. The results are as follows. (1) Heavy fog happens frequently in late autumn and early spring in Guizhou. The occurrence time period of the highest frequency is from 02:00 to 09:00 BT, reaching the peak at 07:00 BT. (2) The southwest, central, eastern and northern parts of Guizhou are the foggy areas from west to east. (3) Frontal fog mainly appears in the central and western Guizhou. The most extensive range covers about 20 county stations, and the duration can be 10-13 h. Some single station can have fog more than 60 h. Radiation fog mainly appears in the central and eastern Guizhou. The widest range can be close to 40 county stations, far more than the frontal fog range, and the duration is relatively short. (4) The 10 min average wind speed is 0-3 m?s-1, the relative humidity is 97%-100%, and the difference between temperature and dew point is 0-0.5℃. Temperature is in a state of decline at the beginning or before the formation of fog. In the period of extinction, warming is more obvious. The difference in temperature between surface and atmosphere presents a trend from negative to positive or from low to high, which reflects the process in which the nearsurface atmosphere changes from a more stable inversion temperature environment to an unstable environment. The early cooling and later heating up are not obvious in frontal fog, also the temperature has no regular distribution between ground surface and atmosphere, only some cases are in line with frontal fog.