一次秋季冷锋降水过程气溶胶与云粒子分布的飞机观测

Aircraft observation of aerosol and cloud droplet during an autumn cold front precipitation process

利用机载PMS(Particle Measuring Systems)测量系统,对2008年10月4—5日石家庄地区一次冷锋降水云系的3次气溶胶和云粒子探测资料进行了分析。结果表明,冷锋过境降水前后,气溶胶粒子分布差异较大。降水发生前,气溶胶粒子平均数浓度约为103cm-3,平均直径为0.95μm;气溶胶主要集中于3000m高度以下的对流层低层,云内气溶胶数浓度明显减少。降水发生后,气溶胶粒子平均数浓度约为102cm-3,比降水前约小1个量级,平均直径为1.28μm;气溶胶主要集中于1200m以下的近地面层,其数浓度随高度增加而降低。气溶胶粒子浓度在低层云区内水平变化较小,而在无云区和云下近地层水平起伏较大。云粒子平均浓度比气溶胶小1～2个量级。气溶胶粒子平均谱主要呈双峰型,而云粒子谱主要为单峰型。

Based on the airborne Particle Measuring Systems （PMS）,the aerosol and cloud particle observation data over Shijiazhuang during a cold-front precipitation cloud system on 4—5 October 2008 are analyzed.Results show that the aerosol distribution is obviously different before and after precipitation.Before precipitation,the average number concentration of aerosol is about 103 cm-3 with mean diameter of 0.95 μm.The aerosol particles are mainly concentrated on the low troposphere below 3 000 m and the aerosol concentration obviously decreases in cloud.After precipitation,the average number concentration of aerosol is about 102 cm-3 with mean diameter of 1.28 μm,and the number concentration is about one order of magnitude smaller than that before precipitation.The aerosol particles are mainly concentrated near the surface layer below 1 200 m,and the number concentration decrease with height.Horizontal fluctuation of the aerosol number concentration is smaller （larger） in lower level cloud area （in no cloud area or near the surface layer below cloud area）.The mean number concentration of cloud particle is one or two orders of magnitude smaller than that of aerosol.The average aerosol spectrum is bimodal and the average cloud particle spectrum is unimodal.