基于观测的大气气溶胶散射吸湿增长因子模型研究 ——以2006 CAREBeijing加强观测为例

在2006年北京加强观测期间,以颗粒物－液体转换采集系统(PILS)测量的气溶胶各可溶性离子组分的质量浓度、颗粒物分级采样器(MOUDI)测量的各可溶性离子组分及有机碳(OC)、碳黑(EC)的分级质量谱分布为基础,对离子组分的可能存在形态进行判断,计算了化学组分质量浓度及各化学物种的粒径数谱浓度;利用Mie模型及各化学物种的密度、折射率、吸湿粒径增长因子等参数计算得到外混、内混的粒子群在干燥状态、不同相对湿度下的散射系数,最终计算得到不同化学组分外混、内混状态下的散射吸湿增长因子;将模型模拟的气溶胶散射吸湿增长因子与观测得到的该因子进行对比,发现模拟值与观测值能够在一定误差范围内吻合,实现了该因子的闭合实验.

Modelling research on the aerosol scattering hygroscopic growth factor based on measurement-Taking 2006 CAREBeijing campaign for example

As a part of CAREBeijing campaign, water-soluble ion mass concentration of aerosols were measured with particle-into-liquid sampler as well as the size distribution of water-soluble ion, particulate organic matter and elemental carbon measured by the MOUDI sampler. Based on these measurements, the existence patterns of each chemical species were assumed and reconstructed and then their mass concentration and number size distribution were calculated. Based on the measurements of size-resolved chemistry, relative humidity (RH), and published functional relationships between the chemical composition and water uptake, the aerosol scattering coefficients could be calculated by the Mie theory for the major particle species. The aerosol scattering hygroscopic growth factor f (RH) was then calculated. Closure study could be achieved and results from the closure study showed that the measured and the modeled values of f (RH) agree within measurement uncertainties.