This paper presents a new algorithm for the joint retrieval of surface reflectance and aerosol properties with continuous variations of the state variables in the solution space. This algorithm, named CISAR (Combined Inversion of Surface and AeRosol), relies on a simple atmospheric vertical structure composed of two layers and an underlying surface. Surface anisotropic reflectance effects are taken into account and radiatively coupled with atmospheric scattering. For this purpose, a fast radiative transfer model has been explicitly developed, which includes acceleration techniques to solve the radiative transfer equation and to calculate the Jacobians. The inversion is performed within an optimal estimation framework including prior information on the state variable magnitude and regularization constraints on their spectral and temporal variability. In each processed wavelength, the algorithm retrieves the parameters of the surface reflectance model, the aerosol total column optical thickness and single scattering properties. The CISAR algorithm functioning is illustrated with a series of simple experiments.
Govaerts, Y., & Luffarelli, M. (2018). Joint retrieval of surface reflectance and aerosol properties with continuous variation of the state variables in the solution space - Part 1: Theoretical concept. Atmospheric Measurement Techniques, 11(12), 6589–6603. https://doi.org/10.5194/amt-11-6589-2018