颗粒物吸湿增长特性是卫星遥感反演近地面颗粒物需要解决的关键问题.本文基于北京地区2007-08—2009-08共两年的地基观测资料,计算了该地区颗粒物平均质量消光效率,结果表明该地区颗粒物平均质量消光效率随相对湿度增加而连续平滑增长.相对湿度从20%增长到85%左右时,质量消光效率增长较为平缓,当相对湿度达85%后,质量消光效率急剧增长.在平均质量消光效率基础上,进一步计算了不同湿度下的气溶胶吸湿增长因子,该因子在不同湿度下的变化趋势基本一致,都在6月达到最大值,1月达到最小值.1月至6月,呈上升趋势,7月至12月,呈波动性缓慢下降趋势,12月值略高于1月.最后,基于平均质量消光效率的吸湿增长因子,针对北京地区常用的3种吸湿增长模型进行拟合,研究表明3种模型在北京地区的适用性都比较好,差别不大,模型3稍优于模型2,模型2稍优于模型1.

Hygroscopic growth characteristics of particulate matter are one of the key issues that need to be addressed in satellite remote sensing of ground-level particulate matter. To solve this problem, the characteristics of the extinction properties of particulate matter as they change with air relative humidity need to be understood, and an accurate hygroscopic growth model of particulate matter should be established. A hygroscopic growth model suitable for Beijing is constructed by using the measurements from instruments deployed on the ground. First, the average particulate matter of mass extinction efficiency is calculated based on continuous measurements from the ground sites in Beijing over a period of two years. Result shows that average mass extinction efficiency of particulate matter increases with relative humidity continuously. The increase in the average particulate matter mass extinction efficiency is moderate when relative humidity increased from 20% to 85%, whereas it increased rapidly when relative humidity increased to 85%. Second, the hygroscopic growth factors of particulate matter in different levels are calculated based on the average particulate matter mass extinction efficiency; the change trend with time of the hygroscopic growth factors are consistent, with the maximum value observed in June and the minimum value in January. From January to June, the hygroscopic growth factors increased before gradually decreasing from July to December. Their values in December were slightly higher than those in January. Third, three hygroscopic growth models commonly used in Beijing are fitted based on these hygroscopic growth factors. The three models showed good applicability in Beijing. The third model is slightly better than the second model, and the second model is slightly better than the first. These models can be used in satellite remote sensing of ground-level particulate matter.