New approach to atmospheric correction of satellite ocean color data

摘要

Requirements on accuracy of the atmospheric correction of satellite ocean color data are rather high, and so far attempts to solve this problem as needed have not been quite successful, especially at high latitudes and in coastal waters. New approach to the atmospheric correction problem consists in simultaneous retrieval of the unknown aerosol and ocean reflectances ρ_a(λ_i) and ρ_w(λ_i) from the top-of-the-atmosphere reflectance ρ_t(λ_i) with use of all spectral channels of a satellite sensor in infrared and visible ranges. The approach is based on parameterization of the spectral behavior of ρ_a(λ_i) and ρ_w(λ_i) with help of several basic functions. In this way the problem reduces to determination of several weight coefficients at these basic functions. This allows us to cut drastically the size and number of required lookup tables. The inversion problem is solved by a least square method with inequality constraints. It is shown that the new algorithm results in better agreement with in situ measured ρ_w(λ_i), compared with the standard SeaWiFS algorithm, in Case 2 waters.