基于Fernald-PSO法反演气溶胶激光雷达比及其对斜程能见度的影响

Inversion of Aerosol Lidar Ratio and Its Effect on Slant Visibility Based on Fernald-PSO Method

为了提高斜程能见度的计算精度,提出了一种基于Fernald-PSO法求解气溶胶激光雷达比的方法.首先,以均匀层底部和顶部的大气消光系数相等为条件构建气溶胶激光雷达比和气溶胶消光系数边界值的方程.然后,再以激光雷达数据反演和AERONET网站观测的气溶胶光学厚度相等为条件构造另一参量方程.最后,采用Fernald-PSO法解方程组,用得到的参量反演气溶胶消光系数计算斜程能见度.采用激光雷达和AERONET数据对该方法进行验证,分析气溶胶激光雷达比对斜程能见度反演的影响.结果表明,同一信号气溶胶激光雷达比假设值与计算值相差越大,气溶胶消光系数和斜程能见度的相对误差绝对值也越大,最大误差分别为18.93%和19.90%.

In order to improve the calculation accuracy of slant visibility, a method based on Fernald-PSO is proposed to determine the aerosol lidar ratio. Firstly, the equation of aerosol lidar ratio and aerosol extinction coefficient boundary value is constructed under the condition that atmospheric extinction coefficients are equal at the bottom and the top of the uniform layer of the atmosphere. The second equation is constructed under the condition that aerosol optical depth derived from the lidar signal is equal to that obtained in AERONET. Finally, Fernald-PSO is used to solve equations, and slant visibility is obtained using the inverted aerosol extinction coefficient. The proposed method is verified by lidar and AERONET data, and the effects of aerosol lidar ratio on the slant visibility are analyzed. The results show that for the same signal, the larger difference between the assumed and calculated values of aerosol lidar ratio, the greater relative errors’ absolute value of aerosol extinction coefficient and slant visibility. The maximal errors are 18.93% and 19.90%, respectively.