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

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".