湖北省雨雾天气特征及影响因素研究

Study on characteristics and influencing factors of rain fog events in Hubei Province

基于2016—2019年湖北省81个国家站逐小时降雨量、相对湿度、风向风速、最小能见度等观测资料,结合武汉市环境监测资料,对降水造成的低能见度事件进行统计分析,结果表明,除雾以外,降雨是湖北省低能见度的主要影响天气(33.7%),其中,小雨量级占比最大;在5个不同低能见度区间,雨强微弱的雨雾过程(小时雨量0~1 mm)占比均超60%,是导致低能见度事件的主因;雨雾过程的最低能见度主要分布在500~1000 m,相对湿度在95%~100%占比达85.09%,风速多集中在1~2 m/s的区间、静风频率为0,风向基本为偏北风;湖北省雨雾过程易发生在冬季,这可能与冬季静稳天气下污染物浓度较高有关,全天各时段均可能出现,22时至次日09时是日高发时段,宜昌市和咸宁市是湖北省内雨雾的高发区;典型个例的雨滴谱资料分析显示,雨滴数密度高、下落速度小可能是造成雨雾低能见度的主要因素。

Based on the observation data of rainfall,relative humidity,wind direction,wind speed and minimum visibility of 81 na⁃tional 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 500~1000 m,the proportion of 95%~100%rel⁃ative 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 Prov⁃ince.The analysis of typical examples shows that high raindrops number density and small drop velocity may be the main factors caus⁃ing low visibility of rain fog.