气溶胶粒径吸湿增长与散射吸湿增长的关系

基于成都市2017年10~12月AURORA-3000积分浊度计、AE-31黑碳仪和GRIMM180环境颗粒物监测仪的地面逐时观测资料，以及该时段同时次的环境气象监测数据（大气能见度、相对湿度RH和NO₂质量浓度），通过Mie散射理论与免疫进化算法反演气溶胶粒径吸湿增长因子Gf（RH），并利用光学综合法测量气溶胶散射吸湿增长因子f（RH），探究了Gf（RH）与f（RH）之间的关系.结果表明：当RH<85%，Gf（RH）和f（RH）随RH的增加均表现为平缓式增长；当RH>85%，Gf（RH）和f（RH）随RH的增加则均呈现出爆发式增长.Sigmoid函数f（RH）=17.34/（1+e^{-2.43·Gf（RH）-2.15}]）较好地拟合了f（RH）随Gf（RH）的变化形态，其f（RH）拟合值与测量值之间的决定系数（R²）和平均相对误差（MRE）分别为0.97和4.01%.利用sigmoid函数计算Gf（RH），模拟了观测时段内一次灰霾演化过程中气溶胶的散射系数b_sp（RH）和吸收系数b_ap，二者的模拟值与测量值基本吻合，对应的R²分别为0.99和0.98，MRE分别为2.94%和5.24%.

Relationship between particle size hygroscopic growth and scattering hygroscopic growth

By utilizing the ground-based monitored data at an hourly time step recorded by AURORA-3000 integrating nephelometer, AE-31 aethalometer and GRIMM180 environment particle monitor from October to December 2017 in Chengdu, as well as the coincidental environmental and meteorological data (including atmospheric visibility, relative humidity (RH) and NO₂ mass concentration, respectively), researches in this paper were summarized as follows. Firstly, aerosols particle size hygroscopic growth factor Gf(RH) was retrieved by combining immune evolution algorithm with Mie scattering theory algorithm. Secondly, aerosols scattering hygroscopic growth factor f(RH) was measured with the aid of optical synthetic approach, and then, the relationship between Gf(RH) and f(RH) was further investigated. The results showed that both Gf(RH) and f(RH) grew mildly at RH<85%, while for RH>85%, the pattern changed to explosive growth. Sigmoid function f(RH)=17.34/(1+e^{-2.43·Gf(RH)-2.15}]) could well fit the variation of f(RH) with Gf(RH), and the determining coefficient (R²) and the mean relative error (MRE) between the fitted f(RH) and the measured values are 0.97and 4.01%, respectively. Subsequently, the aerosols scattering coefficientb_sp(RH)] and absorption coefficientb_ap] during an evolution of haze were further simulated with Gf(RH) calculated by the sigmoid function, and the simulated values were in good agree with the measured values. The corresponding R²are respectively 0.99and 0.98, and the corresponding MRE are respectively 2.94% and 5.24%.