Physical Oceanography最新文献

{"title":"Зависимость квантового выхода фотосинтеза от поглощения света фитопланктоном: получение количественных связей для оценки первичной продукции в Черном море","authors":"T. Y. Churilova, V. Suslin, Heidi M. Sosik","doi":"10.22449/0233-7584-2021-1-73-84","DOIUrl":"https://doi.org/10.22449/0233-7584-2021-1-73-84","url":null,"abstract":"Purpose . Based on the results of the investigations that were performed during the scientific cruise and included the water hydrophysical characteristics, the chlorophyll a concentration, the photosynthesis-light dependences, the spectral light absorption coefficients by phytoplankton, and the spectral quantum downwelling irradiance, the dependence of the photosynthesis quantum yield upon the environmental factors was studied with the purpose of adaptation of the developed for the Baltic Sea approach for assessing the photosynthesis quantum yield, to the Black Sea. Methods and Results . Complex hydrophysical and biological studies were carried out at several depths within the photosynthesis zone. Spectral bio-optical parameters were measured in accordance with the modern NASA protocol (2018). The experiments on studying the photosynthesis-light relationship were performed under the temperature and light conditions close to the in situ ones. The quantum yield of photosynthesis was calculated based on the parameters of photosynthesis-light dependences (photosynthesis efficiency, light saturation parameter) and the spectral light absorption coefficients by phytoplankton pigments. It was found out that the main photosynthetic characteristics of phytoplankton including the photosynthesis maximum quantum yield and the portion of photoprotective accessory pigments in the total light absorption by phytoplankton varied with depth within the euphotic zone due to phytoplankton adaptation to the environment factors during the period of water seasonal stratification. The relationship between the photosynthesis quantum yield and the number of solar energy quanta absorbed by the photosynthetically active phytoplankton pigments was revealed. The results of the performed research allowed for modifying the equation for calculating the quantum yield for the Black Sea environment conditions according to the approach developed for the other water areas. Conclusions . For the first time, comprehensive studies carried out in the Black Sea and including the measurements of the photosynthesis-light dependences, the spectral light absorption coefficients by phytoplankton and spectral downwelling irradiance at particular optical depths within the euphotic zone enabled to reveal the equation for calculating the photosynthesis quantum yield, which could be applied for calculating primary production of the Black Sea using the spectral approach based both on the results of in situ measurements and the remote sensing data.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":"37 1","pages":"73-84"},"PeriodicalIF":0.8,"publicationDate":"2021-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42675684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Generation of Vertical Fine Structure by the Internal Waves with the Regard for Turbulent Viscosity and Diffusion","authors":"S. Demyshev, N. Evstigneeva, D. Alekseev, O. Dymova, N. Miklashevskaya","doi":"10.22449/1573-160X-2021-1-20-36","DOIUrl":"https://doi.org/10.22449/1573-160X-2021-1-20-36","url":null,"abstract":"Purpose. The study is aimed at evaluating effectiveness of the procedure of the observational data assimilation using the Kalman filter algorithm as compared to sequential analysis of the hydrophysical fields based on the optimal interpolation method, and at analyzing the mesoscale features of coastal circulation near the western Crimea coast and in the Sevastopol region. Methods and Results. Based on the hydrodynamic model adapted to the Black Sea coastal zone conditions including the open boundary and on the temperature and salinity data from the hydrological survey in 2007, the dynamic and energy characteristics of the Black Sea coastal circulation were calculated with high spatial resolution (horizontal grid is ~ 1.6 × 1.6 km and 30 vertical horizons). The hydrophysical fields were reconstructed using two algorithms of data assimilation: the sequential optimal interpolation and the modified Kalman filter. The kinetic energy changed mainly due to the wind action, vertical friction and the work of pressure forces; the potential energy – due to the potential energy advection and the horizontal turbulent diffusion. The following circulation features were reconstructed: the anticyclonic eddy with the radius about 15 km in the Kalamita Bay in the water upper layer, the anticyclonic eddy with the radius about 15 km between 32.2 and 32.6° E in the whole water layer, the intense current near Sevastopol and along the Crimea western coast directed to the north and northwest, and the submesoscale eddies of different signs of rotation in the upper layer. Conclusions. It is shown that having been taken into account, heterogeneity and non-isotropy of the error estimates of the temperature and salinity fields relative to the correlation function lead to qualitative and quantitative differences in the hydrodynamic fields (amplification of currents, change of the currents’ direction and eddy formations were better pronounced). At the same time, the mean square errors of the thermohaline fields’ estimates decreased. Formation of the anticyclonic eddy with the radius about 15 km in the Kalamita Bay could be related to the current shear instability. Submesoscale eddies with the diameters less than 5 km were formed when the current flowed around the coastline and the bottom topography inhomogeneities.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45896442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the Power of Intensity Interaction between the Solid and Fluid Phases in the Unconsolidated Water-Saturated Sandy Marine Sediments at Shear Wave Propagation","authors":"V. Lisyutin, O. Lastovenko","doi":"10.22449/0233-7584-2021-1-98-112","DOIUrl":"https://doi.org/10.22449/0233-7584-2021-1-98-112","url":null,"abstract":"Purpose. Propagation of a shear wave in sandy marine sediments is considered. The acoustic properties of a shear wave are the phase velocity and the attenuation coefficient. It is known that in dry sandy sediments, the attenuation coefficient is directly proportional to frequency. In the saturated mediums, there are the deviations from this law that implies existence of two physical mechanisms of losses – the intergranular friction and viscous loss. The study is aimed at developing a two-phase theoretical model of the shear wave propagation in the unconsolidated marine sediments, and at identifying the dissipative effects caused by the fluid relative movement in the pore space. Methods and Results. The intergranular friction is modeled using a springpot, which represents an element combing conservative properties of a spring and dissipative ones of a dashpot. The equation of motion is applied, where a part of fluid is assumed to be associated with the media solid phase and another part is considered to be mobile. For a harmonic displacement, the equations of state and the equation of motion yield a new two-phase dispersion relation (the theory of Grain Shearing + Effective Density, or GS + EDs, for short). The results of the GS + EDs theory are compared with the data of the velocity and attenuation measurements taken from the open sources. It is shown that during propagation of the compressional and shear waves, the mechanisms of interaction between the granules, and between the granules and fluid are not similar. Character of the changes in the grain-to-grain friction parameters when the pore space is saturated with fluid, is analyzed. Conclusions. Manifestation of the dissipative effects resulting from the pore saturation with fluid depends on the density of the granules packing. In case of a dense packing, there are no conditions for the fluid relative movement, and the sandy sediments exhibit the property of constant Q-factor. If the packing is loose, the viscous losses make a significant contribution, and the attenuation frequency dependence is nonlinear. The effective pore sizes for the compression and shear waves do not coincide.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48015289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling the Ecological-Socio-Economic System of the White Sea and its Watershed","authors":"V. Menshutkin, N. Filatov","doi":"10.22449/0233-7584-2021-1-113-131","DOIUrl":"https://doi.org/10.22449/0233-7584-2021-1-113-131","url":null,"abstract":"Purpose. The work is aimed at developing a cognitive model of the ecological-socio-economic system of the White Sea (Beloe more) and its watershed (called for short Belomor’e). Unlike the previously developed cognitive models for the region, the new model of the system has a hierarchical structure including five sub-models united by a common management system. The model is intended for obtaining prognostic qualitative assessments of the transformations ongoing in a complex system under various scenarios of nature management and climate change. The model makes it possible to determine different targets, which, in their turn, permit to assess the possibilities of improving the population living standards, the environment rational use and protection, and development of the White Sea region social sphere. These factors constitute an important foundation for achieving sustainable development of the region. The results can serve a basis for constructing a system of quantitative models required to develop the management decision support systems. Methods and Results. The cognitive model of the White Sea is considered to be a tool for synthesizing heterogeneous information about a complex ecological-socio-economic system. The conceptual modeling and the mathematical apparatus of continuous or probabilistic logic are applied. Unlike the traditional cognitive models, the new one implies the variables’ change in time over 100 years. This allows us to describe the relationship between the interaction agents, and to characterize the mechanisms of their mutual adaptation. The time step in the model is preset to be one year. Development of the cognitive models for the White Sea region was supported by the following information: geographic information systems, databases, integrated electronic and paper atlases of the White Sea and its watershed area, original 3D mathematical models of the sea thermohydrodynamics and ecosystem. The patterns of climate change, hydrological conditions and fishing (basic occupation of local population – the Pomors) were studied. At that, the models both for assessing the regional economy state and for forecasting its development are used. Conclusions. A new cognitive model of the White Sea region ecological-socio-economic system was created based on the hierarchical principle. The developed sub-models relate to various fields of knowledge: economy, demography, oceanography, soil and agrophysics. Dynamics of the model elements over 100 years was demonstrated. Besides, it was shown that with the quasi-cyclic climate fluctuations, the economic parameters change insignificantly, whereas they have a noticeable impact upon the population living standards and the White Sea ecosystem. The demonstrated features resulted from the climate change effects upon the White Sea ecosystem are manifested in the fluctuations of water temperature, phyto- and zooplankton biomass and fishing, but the changes in benthos are hardly noticeable. Dependence of ","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49049208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mathematical Modeling the Dynamics of the Bottom Sediments Granulometric Composition in the Balaklava Bay Affected by the Wind Waves","authors":"K. Gurov, V. Fomin","doi":"10.22449/0233-7584-2021-1-85-97","DOIUrl":"https://doi.org/10.22449/0233-7584-2021-1-85-97","url":null,"abstract":"Purpose. Based on the mathematical modeling methods, influence of the wind waves on redistribution of the sand fractions in the semi-closed estuary-type water area is estimated using the Balaklava Bay as an example. Methods and Results. A two-dimensional version of the XBeach model with a constant grid spacing 10 m was used. The characteristics of wind waves were preset using the JONSWAP spectrum. The calculations were carried out for a storm event lasting about 12 hours once a year. The in-situ data on the particle size distribution in the bottom sediments resulted from the monitoring observations in the Balaklava Bay region was used in the numerical experiments. Conclusions. The results of modeling showed that the basic determining factors regulating the sediments movement were the depth and the bottom slope. It is noted that changing of the bottom inclination angle between the isobaths 6–7 and 7–8 m leads to deposition of the large and medium fractions, and in the area between the isobaths 9–10 and 10–12 m – to accumulation of fine sand. It was revealed that in the Balaklava Bay water area, the main redistribution of sand material caused by the storm waves took place within the southern basin, as well as at the bay exit in the coastal zone of the Megalo-Yalo Gulf. This is primarily determined by the features of the Balaklava Bay coast orography, namely, the knee-shaped narrowness separating the northern and southern basins. Nevertheless, in the isolated northern part of the Balaklava Bay being affected by the storm waves, insignificant dynamics of sand material was observed. The fractions of bottom sediments are redistributed from the western coast to the central part of the basin and to the eastern coast of the bay.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45073578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal and Vertical Variability of Currents Energy in the Sub-Mesoscale Range on the Black Sea Shelf and in Its Central Part","authors":"O. Puzina, A. Kubryakov, A. Mizyuk","doi":"10.22449/0233-7584-2021-1-41-56","DOIUrl":"https://doi.org/10.22449/0233-7584-2021-1-41-56","url":null,"abstract":"Purpose. The study is aimed at investigating seasonal variability and vertical distribution of the sub-mesoscale currents energy (scales L = 1 … 10 km, T = 1 … 10 days) in the deep and shelf zones of the Black Sea. Methods and Results. The study is based on the spectral analysis of the results obtained from the NEMO model numerical calculations performed with high spatial resolution 1 km. The analysis shows that the seasonal variability of the submesoscale energy is significantly different in deep and shelf zones of the basin. At the same time, in both regions, seasonal variation of energy of the sub-mesoscale currents with scales L < 10 rm (Esp) is in good agreement with that of the density fluctuations on the same scales. In the central part of the sea, the high values of Esp are concentrated in the upper mixed layer throughout the whole year. The Esp peak is observed in winter at the depths 0–40 m, which indicates the important role of baroclinic instability induced by the inhomogeneous distribution of the mixed layer depth (MLD) in the generation of sub-mesoscale processes. At the same time, in February in the central part of the northwestern shelf, an absolute minimum of (Esp) is observed. This minimum is caused by the complete mixing and barotropization of the water column. The Esp maximum values are observed in the shelf in September – October. This is related to the intensification of the brackish water transport from the river mouths by mesoscale eddies. In the autumn period high values of Esp in the shelf and deep part of the basin are observed in the deeper layer, compare to summer months .Variability of the Esp vertical distribution coincides to the time variation of MLD. Variability of the submesoscale energy is of a pulsating character with the short-term intensifications and weakenings. Such variability is significantly related to the passing of the mesoscale fronts and the cross-shelf water transport caused by the eddies and upwellings, which lead to the increase of the baroclinic instability. Conclusions. Analysis of the seasonal and vertical variability of the submesoscale currents in the Black Sea deep and shelf zones evidences about the decisive role of the baroclinic instability triggered mainly by the heterogeneity of MLD on their dynamics.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45823651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soliton-Like Waves in the Vicinity of the Southern Kuril Islands","authors":"V. Squire, P. Kovalev, D. Kovalev","doi":"10.22449/0233-7584-2021-1-3-19","DOIUrl":"https://doi.org/10.22449/0233-7584-2021-1-3-19","url":null,"abstract":"urpose. This paper focuses on modulated solitons detected in time series of observational data on sea level oscillations in the Sea of Okhotsk, verifying the presence of nonstationary processes within a quantitative framework of methods. Methods and Results. The paper reports an analysis of wave observation data collected using ARW-type, bottom-mounted pressure sensors in the area of the Capes Castricum, Van-der-Lind and Lovtsova in the southern Kuril Islands. The time series obtained were bandpass filtered using hardware with a passband of 20 minutes to 2.5 hours. Residual time series show the presence of wave packets generated at the beginning of the K1 (diurnal) tide, which consistently appear as a group consisting of 5–7 packets. It is shown that the synchronicity between each wave packet and the K1 wave initiation is associated with the cyclic separation of the tidal flow of the K1 oscillation at the elevation in the Urup Strait located between the islands, along with a concomitant spawning of vortices. It is speculated that the vortices generate the detected wave packets, which are each found to encase a cluster of waves with an average period of about 1.6 hours that are attributed to either edge waves or shelf seiches or a combination of both. A numerical model simulation of the detected wave packets was performed using the Korteweg – de Vries equation, confirming that the envelope of the observed wave packets is close to the modeled one and behaves like a soliton. Conclusions. It is shown that synchronous initiation of a wave packet and a K1 wave is associated with the cyclic separation of the tidal flow of the K1 oscillations at a subsurface elevation in the Urup Strait located between the islands, with a concomitant spawning of vortices. The vortices are assumed to generate the detected wave packets. Each packet contains a cluster of waves with an average period of about 1.6 hours, which is conditioned by the period of the edge wave or shelf seiche. Spectral analysis performed for the 4.5-day-long time series with and without the groups of solitons, showed that the wave energy increases in the 0.5–5.5 hour period range when solitons occur. Application of a simple amplitude-based criterion permitted the authors to identify the waves detected in the wave packets as anomalous. Transformation of the time series into normalized time and normalized amplitude coordinates show that all the examples of anomalous wave packets could be modeled using the Korteweg – de Vries time equation","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48512417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Studying Submarine Groundwater Discharge at the Cape Ayia: a Multi-Tracer Approach","authors":"I. Dovhyi, N. Bezhin, D. Kremenchutskii, O. Kozlovskaya, A. Chepyzhenko, A. V. Verterich, Y. Tovarchii, Yu. G. Shibetskaya, D. Y. Chaikin","doi":"10.22449/0233-7584-2021-1-57-72","DOIUrl":"https://doi.org/10.22449/0233-7584-2021-1-57-72","url":null,"abstract":"Purpose. The study of submarine groundwater discharge is one of the most pressing issues of modern hydrogeology and oceanography. The purpose of the paper is to provide a comprehensive study of the submarine groundwater discharge at Cape Ayia using the hydrological, hydrochemical and radiochemical methods, and to determine the flux of submarine groundwater including the nutrients. Methods and Results. The research werecarried out during the coastal expeditions nearby Cape Ayia on March 24, 2019, and on April 22–24, 2019 during the 106th RV “Professor Vodyanitsky” cruise (April 18 – May 13, 2019). The isotopes 226Ra, 228Ra were extracted using the proprietary MnO2-based fibers. After concentration, the sorbent was squeezed to remove excess water, dried and ashed. Then the ash was placed in the Petri dishes and poured with epoxy resin. Activity of the radionuclides was measured on a low-background semiconductor γ-spectrometer with a detector of high-purity germanium (GC3020) 3 weeks after the resin casting. The activity of 226Ra was determined by the daughter radionuclide 214Pb with the energy 351.9 keV (qγ = 37.2 %), and that of 228Ra – by the daughter 228Ac (T1/2 = 6.1 h, qγ = 27.7 %) with the energy 911.6 keV. The basic elements of the main nutrient cycle were determined photocolorimetrically: mineral phosphorus – by molybdenum blue, silicon – by silicon-molybdenum complex. Nitrates (reduced to nitrites) and nitrites were determined by azo dye; ammonium – by indophenol blue also by the photocolorimetric method. Conclusions. Distribution of hydrophysical, hydrochemical and radiochemical parameters in the water area connected with the known submarine groundwater discharges was studied. The distribution of the 226Ra, 228Ra isotopes was studied for the first time. The data on salinity, specific activity of 226Ra, 228Ra and the nutrients concentration permitted to determine the flows of submarine groundwaters in the Cape Ayia area, which amounted to 8220 ± 1200 m3/day. The anthropogenic contribution to pollution of the groundwater forming the submarine sources is shown.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42002607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seawater Salinity Estimating Module Based on the Sound Velocity Measurements","authors":"A. P. Tolstosheev, E. Lunev, S. Motyzhev, V. Z. Dykman","doi":"10.22449/0233-7584-2021-1-132-142","DOIUrl":"https://doi.org/10.22449/0233-7584-2021-1-132-142","url":null,"abstract":"Purpose. Reliability of knowledge about the ocean dynamics and climate variability is largely limited for lack of systematic in situ observations of the sea surface layer salinity, which is one of the basic hydrological parameters determining circulation and stratification of the water masses. The study is aimed at developing an autonomous device for long-term monitoring of salinity in the seawater upper layer. Methods and Results. One of the most effective tools for in situ observations of the ocean upper layer is the global network of surface drifting buoys – drifters. At present, the network consists of more than 1500 buoys, but only a few of them provide sea surface salinity observations within the framework of a limited number of pilot experiments. In the drifters, salinity is calculated by the traditional method using the results of the electrical conductivity and temperature measurements. There are a few problems related both to the principle of determining salinity by this method and to providing long-term stable running of conductivity sensors under the conditions of pollution and biological fouling. A drifter equipped with the module for the sound velocity and temperature measurements used for calculating salinity by an alternative method just aboard the drifter, was developed in Marine Hydrophysical Institute, Russian Academy of Sciences. The sound velocity and temperature module includes a specially designed time-of-flight sound velocity sensor with the fixed base and a quartz temperature sensor. In course of two years, numerous laboratory and in situ tests of several prototypes of the sound velocity and temperature module were performed. The laboratory tests showed that the repeatability limits for the results of the sound velocity measurements in the distilled water were 0.02 m/s. According to the data of the long-term in situ tests performed at intensive biological fouling, the error of salinity estimation resulted from of the sound velocity and temperature measurements were within 0.05 ‰. This result permits to expect that the sound velocity and temperature module parameters will remain stable in real conditions of long-term autonomous operation. Conclusions. The obtained results make it possible to recommend application of the drifters equipped with the modules for the sound velocity and temperature measurements as an effective tool for regular operational monitoring of the salinity field of the upper sea layer.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45045683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dependence of the Photosynthetic Quantum Yield on Phytoplankton Light Absorption: Equations for Assessing Primary Production in the Black Sea","authors":"T. Churilova, V. Suslin, H. M. Sosik","doi":"10.22449/1573-160x-2021-1-67-77","DOIUrl":"https://doi.org/10.22449/1573-160x-2021-1-67-77","url":null,"abstract":"Purpose. Investigations were performed during a scientific cruise to characterize hydrophysical properties, chlorophyll a concentration, photosynthesis-irradiance curves, spectral light absorption coefficients by phytoplankton, and spectral quantum downwelling irradiance. From these results, the dependence of the photosynthetic quantum yield upon environmental factors was studied with the purpose of adapting an algorithm developed for the Baltic Sea so that it can be applied for the Black Sea. Methods and Results. Complex hydrophysical and biological studies were carried out at several depths within the euphotic zone. Spectral bio-optical parameters were measured in accordance with the latest NASA protocols (2018). Experiments to determine the photosynthesis-light relationship were performed under temperature and light conditions similar to those in situ. The quantum yield of photosynthesis was calculated from parameters of photosynthesis-light curves (photosynthesis efficiency, light saturation parameter) and the spectral light absorption coefficients by phytoplankton pigments. It was found out that the main photosynthetic characteristics of phytoplankton, including the maximum photosynthetic quantum yield and the fraction of phytoplankton absorption associated with photoprotective accessory pigments, varied with depth within the euphotic zone, due to phytoplankton acclimation to environment factors during the period of seasonal stratification. The relationship between the photosynthetic quantum yield and the quanta absorbed by photosynthetically active phytoplankton pigments was revealed. The results of this research made it possible to build on the approach developed for other regions and modify the equation for calculating the quantum yield to apply specifically for environmental conditions in the Black Sea. Conclusions. For the first time, comprehensive studies carried out in the Black Sea, including measurements of the photosynthesis-light dependence, spectral light absorption coefficients by phytoplankton and spectral downwelling irradiance as a function of optical depths within the euphotic zone, made it possible to reveal the equation for calculating photosynthetic quantum yield. This new equation can be applied for calculating primary production of the Black Sea using a spectral approach, based both on the results of in situ measurements and remote sensing data.","PeriodicalId":43550,"journal":{"name":"Physical Oceanography","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43222892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}