粤北冬季气溶胶垂直分布航测研究

Airborne Observation of Wintertime Aerosols Vertical Distributions in Northern Guangdong

关键词:  粤北冬季  气溶胶数浓度  垂直分布  有效直径  飞机观测

Key words:  Winter in Northern Guangdong  Aerosol number concentration  vertical distribution  effective diameter  aircraft observation

摘要:

2024 年 1 月 18—20 日，利用人工影响天气飞机首次对粤北地区开展了大气气溶胶空间分布飞机观测，为评估该区域生态屏障功能的有效性提供基础数据。选取2架次飞行获取的气溶胶、云滴、气象综合观测资料及风廓线雷达、ERA5再分析资料，结合天气形势分析了粤北地区冬季气溶胶数浓度、有效直径及粒径谱的垂直分布特征。结果表明：观测期间，粤北地区在静稳晴好天气下气溶胶数浓度最大值为 1 679 个·cm-3，1 500 m以下数浓度平均值约为 1 000 个·cm-3，有效直径平均值为 0.3 μm。气溶胶平均谱表现为双峰结构，峰值分别为0.14~0.15 μm和0.20~0.22 μm；谱宽随高度减小，1 800 m以下气溶胶谱宽为3 μm，以上则为1 μm。气溶胶平均谱峰值浓度在 500 m 以下为 140~160个·cm-3。气溶胶数浓度总体随高度升高而减小，在边界层顶会出现陡降，逆温层的存在使得数浓度会在多个高度层出现相对高值区。高空输送会影响本地高空气溶胶数浓度的变化。自近地面至高空，整层相对湿度大于80%的大气环境条件有利于可溶性气溶胶粒子在上升过程中吸湿增长。

Abstract:

From 18 to 20 January 2024, aerial observations of atmospheric aerosol spatial distribution were conducted for the first time in northern Guangdong using a weather modification aircraft, establishing baseline data to assess the region's ecological barrier effectiveness. This study analyzes the vertical distribution characteristics of aerosol number concentration, effective diameter, and particle size distribution in winter in northern Guangdong utilizing the data from two flights (including aerosol, cloud droplet, and comprehensive meteorological observations), wind profile radar data and ERA5 reanalysis data, combined with synoptic weather analysis. The results indicate that during the observation period, under stable and clear weather conditions the aerosol number concentration in the northern Guangdong region reached a maximum of 1 679 cm?3, with a mean value of approximately 1 000 cm-3 below 1 500 m and an average effective diameter of 0.3 μm. The average aerosol size distribution exhibited a bimodal structure, with peaks at 0.14-0.15 μm and 0.20-0.22 μm. The average aerosol size distribution width decreased with altitude, measuring 3 μm below 1 800 m and 1 μm above 1 800 m. The peak concentration of aerosol particle size distribution below 500 m was approximately 140-160 particles·cm-3. Overall, aerosol number concentration decreased with altitude, exhibiting a sharp drop at the top of the boundary layer. The presence of an inversion layer resulted in relatively high concentration zones at multiple altitudes. Long- range transport influenced the variation of aerosol number concentration in the upper atmosphere. From the surface to high altitudes, atmospheric conditions with a relative humidity greater than 80% throughout the entire layer facilitated the hygroscopic growth of soluble aerosol particles during their upward transport.