基于Revised IMPROVE方法和MIE方法计算北京地区气溶胶消光系数的对比分析

Contrastive Analysis of Extinction Coefficient of Aerosol in Beijing Based on Revised IMPROVE Equation and MIE Method

目的对比分析IMPROVE方程的改进算法(Revised IMPROVE)和MIE方法在北京地区计算消光系数的适用性。方法基于2012年6月3日至6月30日北京地区大气颗粒物成分的浓度观测数据,分别采用Revised IMPROVE和MIE方法计算颗粒物的消光系数,其中MIE方法的粒径分布采用总量双峰分布体积谱和化学组分体积谱两种方案进行循环试验获取最优拟合结果,使用散射积分浊度计和黑碳仪的实测数据对计算结果进行对比分析。结果Revised IMPROVE方程、总量双峰体积谱MIE方法和化学组分体积谱MIE方法都能较好地计算出了大气颗粒物消光系数,与观测结果回归方程的相关系数R分别达到0.952、0.9686和0.9734。体积谱分布参数的循环试验方法还同时可以获得气溶胶的体积谱分布参数,总量双峰体积谱和化学组分体积谱MIE方法得到的细颗粒和粗颗粒几何平均粒径分别为0.74、7.5μm和0.48、6.0μm。结论采用化学组分体积谱MIE方法计算的消光系数与观测结果最为接近,Revised IMPROVE方程也有较好的准确性,采用化学组分体积谱MIE方法得到的颗粒物体积谱峰值与实际观测结果也较为一致。

Objective To compare and analyze the applicability of the Revised IMPROVE equation and MIE method for calculation of the extinction coefficient of aerosol in Beijing.Methods Based on the observation data of atmospheric particulate matter concentration in Beijing from June 3 to June 30,2012,the extinction coefficient of particulate matter was calculated by Revised IMPROVE and MIE methods respectively.The particle size distribution of MIE method was based on the total bimodal distribution volume spectrum and the chemical composition volume spectrum of the two schemes were cycled to obtain the best fitting results.The calculated results were compared and analyzed with the measured data of integrating nephelometer and aethalometer.Results The Revised IMPROVE equation,the total bimodal volume spectrum MIE method and the chemical composition volume spectrum MIE method could calculate the extinction coefficient of atmospheric particulate matter.The correlation coefficient R of the regression equation with observation results reached 0.952,0.9686 and 0.9734,respectively.The cyclical test method of the volume spectrum distribution parameter can also obtain the volume spectrum distribution parameters of the aerosol,and the peaks of the fine particles and the coarse particles obtained by the total bimodal volume spectrum and the chemical composition volume spectrum MIE method were 0.74,7.5μm and 0.48,6.0μm respectively.Conclusion The extinction coefficient calculated by the chemical component volume spectrum MIE method is the closest to that of the observation.The Revised IMPROVE equation also has high accuracy.The peak volume spectrum of particles obtained by the chemical component volume spectrum MIE method is also consistent with the actual observation results.