不同气象条件下的气溶胶时空分布特征

利用2012年3月20-24日的激光雷达回波数据和粒子计数器采样的气溶胶数浓度数据,分析了测点近地面及其上空的气溶胶垂直消光系数、数浓度等时空分布特征,研究了风向、风速、RH(相对湿度)对近地面气溶胶分布的影响.结果表明:①阴霾天气气溶胶垂直消光系数在0.01 ～1.0之间,边界层高度在1 km以下,到达边界层顶时消光系数产生突变；晴天气溶胶垂直消光系数在0.01 ～0.2之间,边界层高度在1.5 ～2.5 km.②阴霾天和晴天中近地面气溶胶数浓度变化规律一致,上午08:00左右开始增加,随温度升高呈下降态势,在傍晚达最小值后又略微增长并产生次高峰,夜间继续呈下降趋势.③风向为东北偏东风时大气气溶胶的数浓度较大；风速增大,有利于气溶胶垂直输送和扩散,导致气溶胶数浓度减小.④气-粒转化过程中,RH增大有利于气溶胶粒子由爱根核向积聚模态凝结.⑤RH较小时,其与气溶胶数浓度呈正相关,而当RH增至74％时二者呈负相关.

Research on the Temporal and Spatial Distribution of Atmospheric Aerosols under Different Meteorological Conditions

Based on the observation data collected by the lidar and the optical particle counter during 20^th-24^th, March, 2012, temporal and spatial characteristics of the aerosol vertical extinction coefficient and the distribution of number concentration were analyzed. Meanwhile, wind speed and relative humidity on the aerosol number concentration were studied combined with meteorological parameters observation results and effects of wind direction. The results showed that:1) the extinction coefficient of haze day changed significantly, of which value ranged between 0.01and 1.0, and the height of boundary layer was lower than 1km. On sunny days, the extinction coefficient ranged between 0.01-0.2and the height of boundary layer was between 1.5to 2.5km; 2) various trends for number concentrations of atmospheric aerosols were similar on haze days and sunny days, increased around 08:00, with the downward trend in temperature, to minimum and then slightly increased to a peak value in the evening, fell in night; 3) while the wind directions were between from northeast to easterly,atmospheric aerosol number concentration was relatively large. Increasing wind speed facilitates the aerosol vertical transmission and diffusion, to make the number concentration decrease; 4) during the gas-particle conversion process, increasing relative humidity was conducive to giant nuclear condensation to aerosol particles of accumulative mode; 5) when relative humidity was small, particle number concentration and relative humidity showed a positive correlation, but if the relative humidity continues to increase to a certain extent, in this paper was 74%, the negative correlation appeared.