一次太行山焚风对霾强度的影响分析

摘要

Utilizing the NCEP reanalysis data,and the every 5 minute data of ground automatic weather station,laser radar,wind profiler and microwave radiometer,we analyzed the changes of haze intensity in a typical fohn process in Shijiazhuang during the winter of 2015.The results show that the east of Taihang Mountain experienced obvious fohn due to the topographic trough over North China with static and stable weather situation.The fohn led to a rapid decline in humidity,which might cause the rapid rising of horizontal visibility,the decline of PM2.5 concentration and the weakening of haze intensity.Laser radar could visually reflect the changes of boundary layer structure and the concentration of pollutants before and after the fohn.By using the wind profile,we learned that the changes of wind direction (may vary a lot) and speed (may be larger) are obvious below 300 m,which proves the strong pulsation of wind.The horizontal and vertical scales of fohn are 25 km and 1 km,respectively.%利用NCEP再分析资料、逐5 min地面自动气象站、激光雷达、风廓线仪和微波辐射计等资料,对2015年石家庄冬季一次典型焚风过程中霾强度的变化进行了分析.结果表明,在静稳天气形势下,华北地形槽使太行山东麓发生了明显的焚风现象,焚风带来湿度的快速下降,进而引起水平能见度迅速上升、PM2.5浓度迅速下降,霾强度明显减弱.激光雷达可以直观地反映焚风发生前后边界层结构特征和污染物浓度的变化.风廓线仪分析表明,焚风过程300m以下风向、风速的变化明显,表现为风速的加大和风向的多变,说明风场有强的脉动.焚风现象向平原水平推进的距离大概为25 km,垂直影响的高度在1 km以下.