葵花-8卫星AOD资料在CMA-MESO/CUACE

A Study on Effects of Himawari-8 Based AOD Data on 3DVar of CMA-MESO/CUACE CW

CMA-MESO/CUACE CW化学天气耦合模式是自主研发的大气化学耦合模式,目前CMA-MESO/CUACE CW3DVar同化系统实现了地面气溶胶观测可吸入颗粒物PM_(2.5)和PM10的同化,为增强耦合同化系统非常规观测的同化能力,文中在CMA-MESO大气化学天气耦合三维变分同化框架基础上,利用查表法获得气溶胶消光系数,然后建立气溶胶光学厚度(AerosolOpticalDepth,AOD)和气溶胶组分之间关系的观测算子、切线性观测算子和伴随观测算子,实现AOD观测资料的同化应用。针对2016年12月18-20日华北、黄淮地区一次污染天气过程进行同化预报试验,试验结果表明同化葵花-8卫星(Hi‐mawari-8)气溶胶光学厚度观测后,PM_(2.5)分析的重污染区范围有所扩大,山西东南部分析与实况分布更为接近,但是山东大部地区PM_(2.5)分析偏强,与观测相比PM_(2.5)质量浓度存在高估。同时同化Himawari-8 AOD观测和地面气溶胶站点观测的PM_(2.5)分析最优,分析与观测距平相关系数最高,平均偏差、均方根误差及标准差最小。重污染区的PM_(2.5)预报检验结果表明,同化Himawari-8AOD观测对大于350µg·m^(-3)量级PM_(2.5)预报正贡献可以持续到48 h,但整体来说,同时同化Himawari-8AOD观测和地面气溶胶站点观测对各个量级的PM_(2.5)质量浓度预报质量最优。

The CMA-MESO/CUACE CW is an atmospheric chemistry coupled model independently developed by China.At present,the CMA-MESO/CUACE CW 3DVar system realized the assimilation of ground-based aerosol observations of PM_(2.5) and PM10.In order to enhance the assimilation capability of the coupled assimila‐tion system for non-conventional observations,based on the CMA-MESO three-dimensional variational assimila‐tion framework of atmospheric chemical weather coupled system,the aerosol extinction coefficient is obtained by using the look-up table method.And then the observation operator,the tangent linear operator and the adjoint operator are established using the relationship between aerosol optical depth(AOD)and aerosol components.The assimilation tests were carried out for a haze process in North China on December 18-20,2016.The results show that after assimilating the AOD observations from the Himawari-8 satellite,the heavily polluted area of the PM_(2.5) is enlarged,and the analysis in southeastern Shanxi is closer to the actual situation,but the analysis of PM_(2.5) in the majority of the Shandong region is overestimated.The simultaneous assimilation of Himawari-8 AOD observations and ground-based aerosol concentration observations test is the best for the analysis of PM_(2.5),it has the highest correlation coefficients(ACCs)and the smallest mean bias,root-mean-square error and stan‐dard deviation.The PM_(2.5) forecast results in the heavily polluted area showed that the positive contribution of the assimilated Himawari-8 AOD observations to the PM_(2.5) forecasts for the>350μg·m^(-3) magnitude could be sustained up to 48 h.However,the simultaneous assimilation of the Himawari-8 AOD observations and the ground-based aerosol site observations had the best test scores of PM_(2.5) forecasts for each magnitude.