北京地区基于化学组分的夏季气溶胶吸湿特性

利用吸湿增长光散射测量系统、黑碳仪和气相色谱质谱联用仪等仪器，于2019年7月15日~8月4日在北京地区开展了为期21d的大气气溶胶观测实验.观测期间北京市区于7月27日出现短暂的轻度污染，并在7月29日出现强降水天气.结果显示：北京市区夏季大气污染变化剧烈且短暂，大气气溶胶散射吸湿增长因子f（RH）呈现平滑连续的特点，并且降水会对f（RH）造成显著影响.7月27日PM_2.5的平均质量浓度为（92.54±47.05）μg/m³；，表现出较为剧烈的污染变化.7月28~30日平均散射吸湿增长因子f（80%±1%）分别为（1.50±0.35），（1.43±0.36）和（1.48±0.25），反映了降水对于大气气溶胶的湿清除作用.最后利用实验数据估算粒径吸湿增长因子gf（RH），并建模研究f（RH）和gf（RH）的关系，模型精度R²最高可达0.698.

An experimental study on aerosol hygroscopic properties during the summer in Beijing based on chemical composition

With Aerosol Conditioning System (ACS1000), aethalometer (AE33) and gas chromatography/mass selective detector (GC/MSD), an experimental study on the atmospheric aerosol in Beijing was conducted from July 15 to August 4, 2019. There was a short-term air pollution process on July 27 and a strong precipitation on July 29 during the observation. This pollution process in Beijing was short and the concentrations of the pollutants changed dramatically. A continuously increasing tread of f(RH) was observed in the experiment, and the measurements indicated that the precipitation had a great impact on the f(RH). The average concentration of PM_2.5 on July 27 was (92.54±47.05) μg/m³ with a dramatic variation. The average scattering enhancement factors for f(80%±1%) from July 28 to July 30 were (1.50±0.35), (1.43±0.36) and (1.48±0.25), respectively. Furthermore, the experimental data were used to develop a quantitative model between f(RH) and gf(RH) for estimating the hygroscopic growth factor gf(RH). The result of the f(RH)-gf(RH) relationship model showed a good performance, and its R² could reach to 0.698.