On the spatial–temporal variations in the chlorophyll-a concentration on the Peter the Great Bay shelf during the winter–spring phytoplankton bloom according to satellite and subsatellite data

Abstract

Chlorophyll-a concentration (C_chl) variations in the cross section within and outside the Peter the Great Bay shelf during different stages of the winter–spring phytoplankton bloom in 2003–2005 has been considered based on a ship (obtained during the R/V Akademik M.A. Lavrent’ev voyage of February 26 to March 9, 2003) and MODIS-Aqua spectroradiometer and the SeaWiFS color-scanner satellite data. A comparison of the C_chl variability obtained from the ship and satellite data indicates that these data are inconsistent. According to satellite data obtained at the MUMM atmospheric correction, the C_chl variability is distorted less than the NIR-correction data. Studying the variations in the coefficients of light absorption by the detritus and yellow substance (a_dg) and light backscattering by suspended particles (b_bp), C_chl, chlorophyll-a fluorescence (F_chl) according to the satellite data allow us to state that the variations in the discrepancy between the satellite and ship C_chl values are mainly caused by the variations in the content of the detritus and yellow substance in water. Based on the satellite data, it has been revealed that the a_dg values increase with increasing wind mixing after the phytoplankton bloom (about 2–5 km areas where the a_dg, C_chl, F_chl, and bbp values abruptly increased in 2005, apparently due to eddy formation). It has been indicated that the F_chl characteristic, which is close to C_chl, increases when the favorable conditions for the phytoplankton bloom deteriorate. Therefore, this characteristic cannot be used to identify C_chl under the indicated conditions.