Characterization of different water types in the Kerch Strait based on shipborne remote optical measurements
V.V. Rostovtseva, A.S. Izhitskiy, B.V. Konovalov
P.P. Shirshov Institute of Oceanology, Moscow, Russia
Keywords: optical passive remote sensing, hyperspectrometer, suspended matter, phytoplankton, colored organic matter, Secchi disk, water temperature and salinity profiles, anthropogenic impact
Abstract
Study of the state of the Kerch Strait water area was carried out using data from a portable three-channel hyperspectrometer EMMA (Ecological Monitoring of Marine Areas), operating from board a moving vessel during daylight hours with a resolution of several meters along the route. Based on the measured spectra of the sea spectral radiance coefficient, the spectra of the light absorption index by water in the Kerch Strait were calculated. Verification of these data was carried out at the stations by measurements of Secchi disk visibility depth. The concentrations of the three main natural components averaged over the depth of light penetration into the water column were calculated from the spectra of total light absorption by water. They were compared with measurements in surface water samples taken along the route. The discrepancy in these estimates in some areas indicates a nonuniform depth distribution of the components, which was confirmed by vertical sounding at the stations; these areas are not used for calibration of remote sensing results. The EMMA data showed the distribution of the natural components in the water area of the Kerch Strait averaged over the depth of light penetration. It also made it possible to estimate some characteristics of the anthropogenic impact recorded by satellites.
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