Adjustment of Color Indices for the Far East Region with the Use of MUMM Atmospheric Correction

Biooptical parameters of seas of the Far East region retrieved from the MODIS/AQUA radiometer data are analyzed. The results of two main atmospheric correction algorithms, which are based on the assumptions of the absence of water-leaving radiance in the near-IR spectral bands (NIR) and the stability of the sea water spectral shape in this range (MUMM) are compared. Verification was carried out with the use of data from Japanese and Korean AERONET-OC stations. An approach to improving the results of MUMM atmospheric correction via regional adjustment of the color indices is considered. The MUMM correction after adjustment is not inferior to NIR correction in terms of the calculation accuracy of chlorophyll a concentration. It is found that the recommended NIR correction yields negative values of the remote sensing reflectance Rrs at a wavelength of 412 nm in 10% of cases. These cases correspond to highly trophic waters and are accompanied by an overestimation of the chlorophyll-a concentration by an average of 1.8 times. The suggested correction of color indices does not yield negative Rrs values and provides significantly lower errors in the color indices in the blue spectral range than the NIR algorithm. The suggested approach ensures more reliable estimates of biooptical parameters of seas based on satellite data.