关键词: 降水, 大雾, 能见度, 暖平流, 变温

Abstract: Based on the ground meteorological monitoring information, NCEP/NCAR reanalysis data and wind profiler radar data, a heavy fog process induced by a rainfall event in southern Jiangsu Province on 2 April 2016 was analyzed comprehensively. The results indicate that the high surface air temperature accelerated water vapor evaporation before the rainfall, which prompted the decrease of visibility, while the water vapor was condensed to cooling fog under the influence of weak cold air at the later stage of rainfall weakening, and resulted in sharply decreasing of visibility to the minimum value, which was the main reason of the inconsistency of occurrence time between the lowest visibility and the biggest rainfall intensity. Warm advection and positive variable temperature were obvious before the rainfall, which was beneficial to the construction of inverse temperature structure during the rainfall. The low height of inversion layer and the strong reverse temperature played an important role for decreasing of visibility. The vertical wind speed in lower layer sharply increased at the strongest stage of rainfall, so the urgent wind speed, strong rainfall and low visibility caused the occurrence of traffic accident.

Key words: precipitation, heavy fog, visibility, warm advection, variable temperature