南昌昌北机场雾的分类特征与统计分析

Classification Characteristics and Statistical Analysis of Fogs at Nanchang Changbei Airport

利用南昌昌北机场人工和自动观测数据、中国气象局提供的常规地面观测和探空资料以及中国环境监测总站提供的南昌市9个站的逐小时空气质量指数(AQI)数据,对2013年9月至2017年9月南昌昌北机场的76次雾过程进行分类统计,结果表明:昌北机场的雾主要出现在11—5月,多生成于04—10时,消散于06—14时,持续时间多在4 h以内,以雨雾居多,其次是辐射雾,再次是平流辐射雾,而平流雾最少。昌北机场的雾与空气质量密切相关,雾生成前AQI大都有上升趋势,多数为54~100,雨雾时AQI最大,常有轻度到重度污染。雨雾多发于秋、冬、春季的低空暖湿切变线与地面倒槽之间,多在连续小雨或毛毛雨后出现,生成前地面能见度长时间维持低位,生成后波动不大,能见度多为600~800 m。辐射雾多发于深秋至次年初春的弱高压中,常在雨后云层打开后的早间生成,日出后逐渐消散,逆温层底越高持续时间越长;雾生成前地面湿度递增,生成后能见度多在200~600 m。平流辐射雾多发于早冬和春季的入海高压后部弱暖平流中,生成前地面湿度突增,生成后能见度多在200~700 m。平流雾多发于春、夏季低空切变线以南地面鞍型场中,常在切变线北抬、雨停后出现,能见度多在400~600 m。

Based on the artificial and automatic observed data at Nanchang Changbei Airport,the conventional surface observations and sounding data provided by China Meteorological Administration,and the hourly air quality index(AQI)data of 9 stations in Nanchang from China National Environmental Monitoring Centre,76 fog events from September 2013 to September 2017 at Changbei Airport are classified and statistically analyzed.The results show that the fogs of Changbei Airport mainly occur in November to May,they mostly form in the period 04:00-10:00 BT,and dissipate in 06:00-14:00 BT,mostly lasting less than 4 hours.Rain fog occurs most,followed by radiation fog and advection-radiation fog,and advection fog appears the least.The fogs of Changbei Airport are closely related to the air quality.The AQI often has an upward trend before fog occurs,with the value ranging within 54-100.The AQI in rain fogs is the largest,often accompanied by mild to severe pollution.Rain fogs mainly occur between the low-level warm and wet shear lines and the inverted trough on surface in autumn,winter and spring.They often form after continuous light rain or drizzle.The visibility maintains at a low level,mostly 600-800 m,for a long time before the fogs are formed,and keeps stable.Radiation fogs usually occur in the weak high pressure from late autumn to early spring of the next year.They often form in the morning after rain stops and the sky clears,and gradually dissipates after sunrise.They last longer if the bottom of inversion layer is higher.Radiation fogs form after the gradual increase of humidity,and the visibility is mostly 200-600 m.Advection-radiation fogs mainly occur in the weak warm advection behind the high pressure moving east to the sea in early winter and spring.They form generally after the rapid increase of humidity,and the visibility is mostly 200-700 m.Advection fogs usually occur in the surface saddle pressure field south of the low-level shear line in spring and summer.They are generated after the end of rain induced by a north lift of the shear line,and the visibility is mostly 400-600 m.