关键词: 低能见度, 降雨强度, 雨雾, 预报, 湖北省

Abstract: Based on the observation data of rainfall, relative humidity, wind direction, wind speed and minimum visibility of 81 national stations in Hubei Province from 2016 to 2019, and combined with the environmental monitoring data of Wuhan, this paper makes a statistical analysis of the low visibility events caused by precipitation. The results show that in addition to fog, rainfall is the main impact of low visibility in Hubei Province （33.7%）, among which, the proportion of light rain is the largest. The proportion of rain fog process （hourly rainfall 0~1 mm） in five different low visibility ranges is more than 60%, which is the dominant factor leading to low visibility events. The lowest visibility of rain fog process is mainly distributed in 500~1 000 m, the proportion of 95%~100% relative humidity is 85.09%, the wind speed is mostly concentrated in the interval of 1~2 m/s, the static wind frequency is 0, and the wind direction is basically northerly. Hubei rain fog process is easy to occur in winter, which may be related to the high concentration of pollution in winter static and stable weather. Rain fog process may occur in all periods of the day, the period from 22：00 to 09：00 of the next day is the daily high incidence period, and Yichang City and Xianning City are high incidence areas of rain fog in Hubei Province. The analysis of typical examples shows that high raindrops number density and small drop velocity may be the main factors causing low visibility of rain fog.

Key words: low visibility, precipitation intensity, rain fog, forecast, Hubei Province