Physical Oceanography Physical Oceanography 1573-160X 20240101 Analysis of observations and methods of calculating hydrophysical fields in the ocean Research Article Spectral Reflectance Coefficient, Color Characteristics and Relative Transparency of the Black Sea Waters in Spring, 2019 and 2021: Comparative Variability and Empirical Relationships https://orcid.org/0000-0003-0526-4083 I-1595-2015 23004799100 Korchemkina E. N.
Russian Federation
korchemkina@mhi-ras.ru https://orcid.org/0000-0002-4086-1687 AAB-5303-2019 57192647961 Mankovskaya E. V.
Russian Federation
emankovskaya@mhi-ras.ru Marine Hydrophysical Institute of RAS Sevastopol Russian Federation 28 02 2024 31 1 3 17 24 03 2023 04 05 2023 15 11 2023 Copyright ©; 2024, E. N. Korchemkina, E. V. Mankovskaya 2024 E. N. Korchemkina, E. V. Mankovskaya https://creativecommons.org/licenses/by-nc/4.0/ https://physical-oceanography.ru/repository/issues/2024/01/01/

Purpose. The work is purposed at studying spatial variability of the sea reflectance coefficient using the field data, as well as at obtaining empirical relationships between the colorimetric and bio-optical characteristics and comparing them with the already published data.

Methods and Results. The measurement data on spectral reflectance coefficient of the water column and the Secchi disk depth obtained in the expeditions of the R/V Professor Vodyanitsky in the northern and northeastern parts of the Black Sea in April 18 – May 13, 2019 and April 22 – May 8, 2021 were used. Based on the reflectance spectra, the following color characteristics were calculated: dominant wavelength, water color purity, hue angle, and the inherent optical characteristics (absorption of dissolved organic matter and backscattering by suspended particles). Variability of the sea reflectance coefficient and its color characteristics was analyzed for similar periods in spring 2019 and 2021. For the combined data for 2019 and 2021, the relationships between the Secchi disk depth and the reflectance coefficient at maximum, as well as the dominant wavelength were obtained and compared to the known data. For the first time, the empirical relationships connecting the hue angle with the dissolved organic matter absorption and the backscattering by suspended particles were obtained to calculate the inherent optical characteristics of the Black Sea waters.

Conclusions. The distribution of the reflectance coefficient observed in 2019 is more typical of late spring, whereas the similar distribution observed in 2021 rather indicates the continuing winter-spring development of phytoplankton communities that is typical of the deep part of the Black Sea waters in the years with cold winters. Significant correlations between the colorimetric and bio-optical parameters of seawater were established. They can be used as a part of the empirical and semi-analytical algorithms for comprehensive assessing (including application of remote sensing data) the hydrooptical characteristics of the Black Sea waters.

 spectral reflectance coefficient Secchi disk depth dominant wavelength color purity hue angle chromaticity diagram absorption by dissolved organic matter particles backscattering Secchi disk ocean color The work was carried out within the framework of a state assignment on topics No. FNNN-2024-0016 and No. FNNN-2024-0012, the data were obtained in the 106th and 116th cruises of the R/V Professor Vodyanitsky (Center for Collective Use "R/V Professor Vodyanitsky" of the Federal State Budgetary Scientific Institution of Federal Research Center "A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS").

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REFERENCES SmithT. GuildJ. The C.I.E. Colorimetric Standards and Their Use Transactions of the Optical Society 1931 33 3 73 134 10.1088/1475-4878/33/3/301 Van der WoerdH. J. WernandM. R. True Colour Classification of Natural Waters with Medium-Spectral Resolution Satellites: SeaWiFS, MODIS, MERIS and OLCI Sensors 2015 15 10 25663 25680 10.3390/s151025663 GarabaS. P. FriedrichsA. VoßD. ZielinskiO. Classifying Natural Waters with the Forel-Ule Colour Index System: Results, Applications, Correlations and Crowdsourcing International Journal of Environmental Research and Public Health 2015 12 12 16096 16109 10.3390/ijerph121215044 Van der WoerdH. J. WernandM. R. Hue-Angle Product for Low to Medium Spatial Resolution Optical Satellite Sensors Remote Sensing 2018 10 2 180 10.3390/rs10020180 LeeM. E. ShybanovE. B. KorchemkinaE. N. MartynovO. V. Determination of the Concentration of Seawater Components based on Upwelling Radiation Spectrum Physical Oceanography 2015 6 15 30 10.22449/1573-160X-2015-6-15-30 KorchemkinaE. N. MankovskayaE. V. Relationships between Bio-Optical Parameters of the Black Sea Waters and Spectral Reflectance Coefficient in Spring 2019 Fundamental and Applied Hydrophysics 2022 15 3 53 64 10.48612/fpg/47v1-8k56-g93n MorelA. Optical Properties of Pure Water and Pure Sea Water JerlovN. G. NielsenE. S. Optical Aspects of Oceanography New York Academic Press 1974 1 24 SmithR. C. BakerK. S. Optical Properties of the Clearest Natural Waters (200–800 nm) Applied Optics 1981 20 2 177 184 10.1364/AO.20.000177 ChurilovaT. SuslinV. KrivenkoO. EfimovaT. MoiseevaN. MukhanovV. SmirnovaL. Light Absorption by Phytoplankton in the Upper Mixed Layer of the Black Sea: Seasonality and Parametrization Frontiers in Marine Science 2017 4 90 10.3389/fmars.2017.00090 ChurilovaT. MoiseevaN. EfimovaT. SuslinV. KrivenkoO. ZemlianskaiaE. Annual Variability in Light Absorption by Particles and Colored Dissolved Organic Matter in the Crimean Coastal Waters (the Black Sea) Proceedings of SPIE 2017 10466 104664B 10.1117/12.2288339 MikaelyanA. S. ChasovnikovV. K. KubryakovA. A. StanichnyS. V. Phenology and Drivers of the Winter-Spring Phytoplankton Bloom in the Open Black Sea: The Application of Sverdrup's Hypothesis and Its Refinements Progress in Oceanography 2017 151 163 176 10.1016/j.pocean.2016.12.006 FinenkoZ. Z. MansurovaI. M. SuslinV. V. Temporal Dynamics of Phytoplankton Biomass in the Surface Layer of the Black Sea According to Satellite Observations Oceanology 2022 62 3 358 368 10.1134/S0001437022030043 MankovskyV. I. Color Characteristics of Waters and Their Correlation with Secchi Depth Oceanology 2017 57 5 611 614 10.1134/S0001437017050101 MankovskyV. I. Influence of the Composition of Suspended Matter on the Secchi Disk Depth Atmospheric and Oceanic Optics 2019 32 3 284 288 10.1134/S1024856019030138 Man'kovskyV. I. GrinchenkoD. V. Suspended Matter and Its Composition from the Data on Light Scattering at the Large-Scale Polygon in the Northern Part of the Tropical Atlantic Ocean Physical Oceanography 2018 25 3 235 246 10.22449/1573-160X-2018-3-235-246 Man'kovskiiV. I. TolkachenkoG. A. ShibanovE. B. MartynovO. V. KorchemkinaE. N. YakovlevaD. V. KalinskiiI. A. Optical Characteristics of Coastal Waters and Atmosphere near the South Coast of the Crimea at the end of Summer 2008 Physical Oceanography 2010 20 3 207 230 10.1007/s11110-010-9079-x WoźniakS. B. DareckiM. SaganS. Empirical Formulas for Estimating Backscattering and Absorption Coefficients in Complex Waters from Remote-Sensing Reflectance Spectra and Examples of Their Application Sensors 2019 19 18 4043 10.3390/s19184043 MorelA. PrieurL. Analysis of Variations in Ocean Color Limnology and Oceanography 1977 22 4 709 722 10.4319/lo.1977.22.4.0709