一次北部湾海雾天气过程的大气边界层特征分析

Characteristic Analysis of Atmospheric Boundary Layer for a Sea Fog Weather Process in Beibu Gulf

利用常规地面和高空气象观测资料、风廓线雷达和NCEP/NCAR再分析资料,分析了2016年2月11~13日导致北海-涠洲岛航线停航的典型平流型海雾天气过程的环流形势、边界层特征。结果表明:此次海雾天气过程,近地面层风速较小约3~5m·s^-1,为东南风;850hPa附近,有12~15m·s^-1的西南风急流;500m以下,具有一定的垂直风切变,水平风切变越小,海雾天气越严重。海雾期间的大气层结为中性状态,混合层厚度低于500m,且混合层厚度越低,能见度也越低,海雾天气越严重。此外,925hPa附近存在逆温层、地面的相对湿度较大(约95%)和温度露点差较小(1~2℃)均是该次海雾天气的明显特征。以上这些大气边界层特征可作为北部湾平流型海雾天气预报的参考依据。

The circulation situation and boundary layer characteristics of the typical advection sea fog weather process which caused the suspension of the Beihai-Weizhou Island route from 11 to 13 February 2016 are analyzed by using the conventional ground and high-altitude meteorological observation data, wind profiler radar and NCEP/NCAR reanalysis data. Results show that during this sea fog process, there is southeast wind (3~5 m·s^-1) near the surface layer, and near 850 hPa is southwest wind jet (12~15m·s^-1). With a certain vertical wind shear below 500 m, the smaller the horizontal wind shear, the severer the sea fog. The atmospheric stratification during sea fog is neutral, and the thickness of mixed layer is less than 500 m. The lower the height of the mixed layer, the lower the visibility and the severe the sea fog weather. In addition, the existence of inversion layer near 925 hPa, the high relative humidity of the ground (about 95%) and the small temperature dew point difference (1~2 ℃) are the obvious characteristics of this process. In brief, the characteristics of boundary layer above can be used as a reference for predicting advection sea fog weather in Beibu Gulf.