云顶以下臭氧对TOMS反演臭氧总量的影响及反演方法的理论研究

目前紫外后向散射反演臭氧总量的所有算法，都将云考虑成不透明的Lambertian反射体，并假定云顶有效反照率不随波长的变化而变化.然而本文通过模拟计算发现，由于云散射、瑞利散射、臭氧吸收三种作用的综合结果，云顶的有效反照率是与波长相关的，即使光学厚度比较大的云，辐射也可由云顶继续向下传输，因而会受到云顶以下臭氧吸收的影响.用V7方法进行反演，模拟计算结果表明：云的出现使得云顶以下，特别是云内光程增强，导致紫外波段的臭氧吸收衰减增大，所以反演出的臭氧总量值比真实值偏大，本文称这种现象为“云吸收效应”，并讨论了该效应的影响因子.最后，在辐射传输模拟的基础上建立一套反演算法，大大减弱了“云吸收效应”的影响.

A theoretical study on the effect of ozone below cloud on total ozone retrieved by TOMS and a new inversion algorithm

Currently all TOMS ozone retrieval algorithms treat cloud as an opaque Lambertian reflector and consider the effective reflectivity of the cloud top height is independent of the wavelength. Our simulation calculation of atmospheric radiative transfer shows that the reflectivity of cloud top height is dependent on the wavelength because of the integrated action of cloud scattering, Rayleigh scattering and ozone absorption. In addition, cloud is not opaque and radiation can penetrate into the cloud even though the optical thick cloud. Simulating calculations using the V7 algorithm show the multiple scattering below the cloud top height, especially in the cloud can enhance the ozone absorption path length. The effect can make the retrieval value of total ozone amount larger than the actual one. We call the phenomena "cloud absorption effect" and make a discussion on the influence parameters. Then, a new inversion algorithm on the basis of simulating calculations is developed under the condition that cloud is present. The new algorithm can reduce the error induced by the "cloud absorption effect".