Проведён анализ изменчивости биооптических показателей прибрежных вод Чёрного моря разной трофности. Показано, что содержание оптически активных компонентов среды оказывает влияние на прозрачность вод и спектральные свойства излучения, проникающего к нижней границе зоны фотосинтеза. Зависимость прозрачности и спектральных характеристик проникающего излучения от биооптических показателей вод описывается степенным уравнением. Полученные данные будут использованы для трансформации спутниковых данных в показатели качества и продуктивности вод.

В ходе научной экспедиции «Европейская Арктика – 2020» на НИС «Академик Мстислав Келдыш» (рейс №80) были проведены измерения концентрации хлорофилла а, спектральных показателей поглощения света пигментами фитопланктона, неживым взвешенным веществом и окрашенным растворенным органическим веществом в верхнем освещенном слое Норвежского и Баренцевого морей, а также в Северном Ледовитом океане в период с 28 июля по 23 августа 2020 г. Установлена высокая вариабельность биооптических характеристик, неоднородность исследованной акватории по относительному вкладу окрашенного растворенного органического вещества в общее поглощение света. Получена связь между общим поглощением света на 438 и 490 нм в поверхностном слое вод и глубиной зоны фотосинтеза.

Purpose. The work is aimed at investigating spatial distribution of the chlorophyll a concentration and the spectral light absorption coefficients by all optically active components in the Azov and Black seas in spring, when the seawater hydrophysical structure changes. Methods and Results. The data collected in the 106th scientific cruise of R/V Professor Vodyanitsky in April 19 – May 10, 2019 were used. The chlorophyll a concentration was measured by the spectrophotometric method. The spectral light absorption coefficients were determined in accordance with the NASA protocol 2018. The optical measurements were performed using the dual-beam spectrophotometer Lambda 35 (PerkinElmer). It was shown that in the surface layer of the Black Sea, the chlorophyll a concentration varied from 0.21 to 1.2 mg/m3. At some stations in the deep-water region, the increased values of this parameter were observed in the lower part of the euphotic zone that was associated with the beginning of seasonal water stratification due to the surface water heating. At these stations, the phytoplankton absorption spectra were more smoothed in the lower part of the euphotic zone than those in the upper layer. In the deep-water region, the non-algal particles contribution to the total particulate light absorption at wavelength 438 nm changed with depth from 40 ± 15 % at the surface to 29 ± 12 % near the bottom of the euphotic zone; whereas in the coastal waters this parameter was almost unchangeable within the water column (54 ± 11 %). No significant change of the colored dissolved organic matter contribution to the total light absorption with depth was revealed (69% on average). In the Sea of Azov, vertical distribution both of the chlorophyll a concentration (6.2 mg/m3 on average) and the spectral light absorption coefficients by all the optically active components was uniform. The non-algal particles contribution to the particulate light absorption was 40 ± 14 %, and the colored dissolved organic matter contribution to the total light absorption constituted 52 ± 6 %. Conclusions. New data on spatial distribution of the chlorophyll a concentration and the spectral light absorption coefficients by the optically active components in the Black and Azov seas were obtained for the spring period when the seawater hydrophysical characteristics changed.

The results of the comparison of the values of the standard satellite product “Chlorophyll a Concentration” recovered from MODIS-Aqua satellite with the results of field measurements in the coastal waters of the Black Sea near Sevastopol from 2009 to 2019 as a part of regular bio-optical monitoring have been presented. Differences between seasons in the nature of the error of the standard satellite product “Chlorophyll a Concentration” using the standard NASA algorithm were established: in spring, a significant underestimation of the values of the standard satellite product “Chlorophyll a Concentration” (up to 2.1 times) at high chlorophyll a concentrations was noted according to the results of the full-scale measurements, and in summer a significant overestimation of the values (up to 3.8 times) at low concentrations was noted. Throughout the year, depending on the season, the error in determining the standard satellite product “Chlorophyll a Concentration” on average varied from ±24 % to ±51 %. To increase the accuracy of determining the chlorophyll a concentration with remote sensing, it is necessary to use a regional approach.

The results of the comparison of the values of the standard satellite product “Chlorophyll a Concentration” recovered from MODIS-Aqua satellite with the results of field measurements in the coastal waters of the Black Sea near Sevastopol from 2009 to 2019 as a part of regular bio-optical monitoring have been presented. Differences between seasons in the nature of the error of the standard satellite product “Chlorophyll a Concentration” using the standard NASA algorithm were established: in spring, a significant underestimation of the values of the standard satellite product “Chlorophyll a Concentration” (up to 2.1 times) at high chlorophyll a concentrations was noted according to the results of the full-scale measurements, and in summer a significant overestimation of the values (up to 3.8 times) at low concentrations was noted. Throughout the year, depending on the season, the error in determining the standard satellite product “Chlorophyll a Concentration” on average varied from ±24 % to ±51 %. To increase the accuracy of determining the chlorophyll a concentration with remote sensing, it is necessary to use a regional approach.