多轴差分吸收光谱技术反演气溶胶消光系数垂直廓线

研究了多轴差分吸收光谱技术(MAX-DOAS)的气溶胶消光系数垂直廓线反演算法. 该算法应用非线性最优估算法, 通过MAX-DOAS测量的氧的二聚体(O₄), 反演气溶胶消光系数垂直廓线和光学厚度(AOD). 首先研究了非线性最优估算法中权重函数、先验廓线协方差矩阵、测量不确定度协方差矩阵的计算方法, 针对中国气溶胶浓度较高且变化剧烈的特征, 设计了非线性迭代方案. 然后在低气溶胶、高气溶胶和抬高型气溶胶三种状态下, 通过计算机仿真模拟验证了MAX-DOAS气溶胶消光系数垂直分布反演算法, 讨论了误差来源. 之后在合肥地区开展了连续观测实验, 并将反演的AOD与CE318太阳光度计对比, 两者的相关性系数达到了0.94. AOD反演的相对误差约为20%. 又将反演的最低层(0–0.3 km)气溶胶消光系数与能见度仪对比, 两者的相关性系数为0.65. 近地面气溶胶消光系数反演的总相对误差约为10%. 模拟验证和对比实验均说明本文研究的气溶胶消光系数垂直廓线反演算法可以较好地获取对流层的气溶胶状态. 关键词： 多轴差分吸收光谱 气溶胶消光系数垂直廓线 气溶胶光学厚度 最优估算法

Retrieving vertical profile of aerosol extinction by multi-axis differential optical absorption spectroscopy

Using the oxygen dimer (O₄ information measured by multi-axis differential optical absorption spectroscopy (MAX-DOAS)), an inversion method of vertical profile of aerosol extinction based on nonlinear optimal estimation algorithm is developed. At first we study how to calculate some parameters (weighting function, the covariance matrices of measurement and a priori) of the algorithm and design nonlinear iteration strategy suited to Chinese region where aerosol usually shows rapid variation and high load. Then this inversion method is verified by computer simulation combined with discussion about error source in three typical cases of low, high and elevated aerosol. After that a continuous observation is reported in the city of Hefei. The aerosol optical depth (AOD) derived from MAX-DOAS is compared with that of CE318 sun photometer and the correlation coefficient is 0.94. The total relative error of AOD is about 20%. In addition the aerosol extinction in the lowest altitude (0-0.3 km) is compared with that of visibility meter and the correlation coefficient is about 0.65. The total relative error of surface-near aerosol extinction is about 25%. Both of simulation verification and comparison experiment indicate that the inversion method can well rebuild the vertical profile of aerosol extinction in the troposphere.
Keywords： multi-axis differential optical absorption spectroscopy vertical profile of aerosol extinction aerosol optical depth optimal estimation method