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The Black Sea coastal nowcasting and forecasting system was built within the framework of EU FP6 ECOOP (European COastalshelf sea OPerational observing and forecasting system) project for five regions: the south-western basin along the coasts of Bulgaria and Turkey, the north-western shelf along the Romanian and Ukrainian coasts, coastal zone aroun...
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... The main river flow is 80% located in the western part of the sea, and this part of the sea is more eutrophicated [55][56][57][58]; in the eastern part of the sea, eutrophication is less and such spatial variability affects the state of the marine ecosystem [59]. A unique feature of the Black Sea is a Rim Current that runs along the continental slope and forms a cyclonic circulation [60,61]. The Black Sea has a complex vertical hydrophysical structure characterized by a cold intermediate layer and a pycnocline separating the waters of the Black Sea proper from the underlying Mediterranean waters [62]. ...
The biogeochemistry of waters is an essential regulator of phytoplankton dynamics, determining the level of species bloom and the change in dominants. This paper investigated the seasonal dynamics of phytoplankton and the nutrient concentrations and their ratios in the northeastern Black Sea in 2017–2021. Two taxonomic groups, diatoms and coccolithophores, determine the seasonal dynamics and significantly contribute to the total phytoplankton biomass. Coccolithophores formed blooms in early June annually, except in 2020. Large diatoms dominated in summer with a biomass exceeding 1000 mg m−3 annually, except in 2019. During the blooms of these taxonomic groups, their contribution to the total phytoplankton biomass exceeded 90%. Each group has characteristic biogeochemical niches in the nitrogen and phosphorus concentration coordinates. The position of the seasonal thermocline regulates the biogeochemistry of the water. With a high-lying and sharp gradient thermocline (the average for five years is 6.87 m), low nitrogen concentrations and a nitrogen-to-phosphorus ratio below the Redfield ratio are created in the upper mixed layer. These conditions are optimal for the dominance of coccolithophores. When the thermocline is deepened (the average for five years is 17.96 m), the phosphorus concentration decreases significantly and the ratio of nitrogen to phosphorus is significantly higher than the Redfield ratio, and these conditions lead to the dominance of large diatoms. The results of experimental studies with nitrogen and phosphorus additives in the natural phytoplankton population confirm the above statements. The addition of phosphorus leads to the increased role of coccolithophores in the total phytoplankton biomass, the addition of nitrogen alone contributes to the growth of large diatoms, and the combined addition of phosphorus and nitrogen in a ratio close to the Redfield ratio leads to the dominance of small diatoms.
... The main river flow is 80% located in the western part of the sea, and this part of the sea is more eutrophicated [55][56][57][58], in the eastern part eutrophication is less and such spatial variability affects the state of the marine ecosystem [59]. A unique feature of the Black Sea is a Rim current that runs along the continental slope and forms a cyclonic circulation [60,61]. The Black Sea has a complex vertical hydrophysical structure characterized by a cold intermediate layer and a pycnocline separating the waters of the Black Sea proper from the underlying Mediterranean waters [62]. ...
Biogeochemistry of waters is an essential regulator of phytoplankton dynamics, determining the level of species bloom and the change of dominants. The paper investigated the seasonal dynamics of phytoplankton and the nutrient concentration and their ratios in the NE Black Sea in 2017-2021. Two taxonomic groups, diatoms, and coccolithophores, determine seasonal dynamics and significantly contribute to the total phytoplankton biomass. Coccolithophores annually, except in 2020, formed bloom in early June. Large diatoms in summer annually, except in 2019, dominated with biomass exceeding 1000 mg m-3. During the bloom of these taxonomic groups, their contribution to the total phytoplankton biomass exceeded 90%. Each group has characteristic biogeochemical niches in the nitrogen and phosphorus concentrations coordinates. The regulation of the biogeochemistry of water is the position of the seasonal thermocline. With a high-lying and sharp gradient thermocline (the average for five years is 6.87 m), low nitrogen concentrations and a nitrogen-to-phosphorus ratio below the Redfield ratio are created in the upper mixed layer. These conditions are optimal for the dominance of coccolithophores. When the thermocline is deepened (the average for five years is 17.96 m), the phosphorus concentration decreases significantly and the ratio of nitrogen to phosphorus is significantly higher than the Redfield ratio, and these conditions lead to the dominance of large diatoms. The results of experimental studies with nitrogen and phosphorus additives in the natural phytoplankton population confirm the above statements. The addition of phosphorus leads to an increased role of coccolithophores in the total phytoplankton biomass, the addition of nitrogen alone contributes to the growth of large diatoms, and the combined addition of phosphorus and nitrogen in a ratio close to the Redfield ratio leads to the dominance of small diatoms.
... Various methods use different assumptions and simplifications in order to make the process feasible, e.g., [19,20]. Despite data assimilation being currently ubiquitous in geosciences, it has so far remained a topic mostly reserved to experts [21,22] The purpose of this paper is to develop a simple and computationally efficient method of implementing DA for a high-resolution child model that is nested into a data-assimilating parent model. The method is mainly intended for smaller academic and operational centres that do not have resources of the same scale as the major ocean forecasting institutions. ...
A simple and computationally efficient method is presented for creating a high-resolution
regional (child) model nested within a coarse-resolution, good-quality data-assimilating (parent) model. The method, named Nesting with Downscaling and Data Assimilation (NDA), reduces bias and root mean square errors (RMSE) of the child model and does not allow the child model to drift from reality. Usually coarser resolution models, e.g., global scale, are used to provide boundary conditions for the nested child model. The basic idea of the NDA method is to use a complete 3D set of output data from the parent model using a process which is similar to data assimilation of observations into an ocean model. In this way, the child model is physically aware of observations via the parent model. The method allows for avoiding a complex process of assimilating the same
observations which were already assimilated into the parent model. The NDA method is illustrated in several simple 2D synthetic cases where the true solution is known. The NDA method reduces the child model bias to the same level as in the parent model and reduces the RMSE, typically by a factor of two to five, occasionally more.
... An essential feature of the Black Sea circulation is the Eastern and Western cyclonic eddies ( Figure 1) situated in the central parts of the sea. The Black Sea characteristic feature is the Rim Current 40-80 km wide, which runs along the continental slope and forms a general cyclonic circulation [7][8][9]. The Rim Current, meandering, forms numerous mesoscale cyclonic and anticyclonic eddies over the continental slope and in the open part of the sea [10]. ...
Based on satellite data from the SeaWiFS, MODIS-Aqua, and MODIS-Terra scanners, the long-term dynamics of coccolithophores in the Black Sea and their large-scale heterogeneity have been studied. During the twenty years in May and June, mass development of coccolithophores population of different intensities was recorded annually. Summer blooms of coccolithophores reached peak levels in 2006, 2012, and 2017, after abnormally cold winters. It was noted that in conditions of low summer temperatures, the blooming of coccolithophores could be significantly reduced or acquire a local character (2004). In the anomalous cold summer of 2001, coccolithophore blooms were replaced by the mass growth of diatoms. Over twenty years, numerous signs of coccolithophores mass development in the cold season have been revealed. Winter blooms develop mainly in warm winters with periods of low wind activity. The formation of a thermocline and the surface layer’s stability are essential factors for initiating winter blooms of coccolithophores. It was noted that after the winter blooms of coccolithophores, their summer growth was poorly expressed. It is shown that during periods of rapid growth, the bulk of coccolithophores is concentrated in the upper mixed layer and thermocline. During the blooming period, the share of coccolithophores in phytoplankton biomass constituted 70–85%. The intensity of coccolithophore’s blooms is associated with the previous diatoms’ growth level. The effect of eddies circulation on the distribution and growth of coccolithophores is considered.
... The operational forecast of the state of waters in coastal regions of the Black Sea is carried out by the Black Sea Coastal Forecasting System (BSCFS), developed within the framework of the EU FP6 ECOOP and FP7 MyOcean European Commission projects [15,[20][21][22][23][24]. This is a subsystem of the operational system of diagnostic and forecasting of the Black Sea in the Marine Hydrophysical Institute; it is based on the global basin-wide model of the Black Sea [15][16][17]. ...
... The BSCFS covers almost whole coast of the Black Sea, except for the northern coast of Turkey, and includes five regions: the southwestern basin along the shores of Bulgaria and Turkey, the northwestern shelf near the shores of Romania and Ukraine, the basin around the Crimean Peninsula, the northeastern zone near the shore of Russia, and the coastal zone of Georgia. Circulation in the coastal zone of Georgia is calculated using the model in z coordinates [25]; for other regions, the BSCM (BlackSeaCoastalModel) σ-coordinate model, which is in fact a version of the Princeton Ocean Model (POM) adapted to physical and geographical conditions of the Black Sea [20,[26][27][28][29][30]. The operational circulation model, which is a base of forecasting the state of waters in the northeastern region of the Black Sea near the coast of Russia (RuReM), is installed in the Zubov State Oceanographic Institute (SOI) [23]. ...
... In this paper, our attention is focused on the upper layer of the Black Sea, many aspects of which in relation of dynamical processes (circulation, wind-driven turbulence, mixed layer forming, heat exchange, wave energy propagation) have been investigated by some authors on the basis of the various numerical models and by processing of measured data's (Friedrich and Stanev, 1988;Oguz et al., 1999a;Korotaev et al., 2003;Kara et al., 2005aKara et al., , 2005cStanev, 2005 The used physical models in context of the mixed layer study differ from each other by coordinate system, methods of solution, grid parameters, parametrization of turbulence and solar radiation penetration schemes (Friedrich and Stanev, 1988 Kvaratskhelia et al., 2018). Moreover, on the basis of BSM-IG at the Institute of Geophysics the high-resolution regional version (RM-IG) is successfully functioning in operational mode (Kordzadze and Demetrashvili, 2011;Demetrashvili et al., 2020), which was developed within the framework of international scientific projects ARENA and ECOOP (Korotaev et al., 2011;Kubryakov et al., 2012). The mentioned BSM-IG and RM-IG were operated in accordance to the constant values of vertical turbulent viscosity and diffusion coefficients and by modified Oboukhov formula (Marchuk et al., 1980), whose numerical values in the case of unstable stratication increasing 20 times, in the appropriate columns Kordzadze and Demetrashvili, 2011). ...
In this paper, the Black Sea upper mixed layer (UML) structures in mid-February by using a 3-D numerical model of the Black Sea dynamics (BSM-IG, Tbilisi, Georgia) are investigated. In order to present the turbulent mixing peculiarities more clearly, a new version of the classical Pacanowski-Philander parameterization formulated by Bennis et al. (2010) for vertical turbulent viscosity and diffusion coefficients is integrated in the BSM-IG. The Black Sea UML homogeneity is estimated using criterion of temperature (△T = 0.2 • C) and salin-ity (△S = 0.15 psu). Besides, mixed layer structures have been investigated according to both values of the Richardson number: Ri T and Ri S , respectively. As result analysis shows: in February UML structures in the temperature fields correspond to the Richardson number specificity, basically, but mixed layer homogeneity reduced in the salinity fields, when Richardson number changed in the following range 0.07 < Ri S ≤ 1, especially, in deep waters of the sea basin.
... The development of effective data-computing systems has led to the creation of the Black Sea nowcasting/forecasting system [4], [6]. [7], [8]. Such an achievement of the Black Sea operative oceanography became possible as a result of close cooperation of oceanologists from the Black Sea countries in the framework of the EU projects ARENA, ASCABOS, ECOOP. ...
Modelling and forecasting of dynamic processes and distribution of various substances of anthropogenic and natural origin in coastal and shelf zones of the seas and oceans are of great interest due to the high anthropogenic load of these zones. The aim of this paper is to present some examples of modelling and short-term forecasting of dynamic fields – the current, temperature and salinity in the easternmost Black Sea covering Georgian sector of the Black Sea and adjacent water area using a high-resolution regional model of the Black Sea dynamics. The z-level regional model is based on a full system of ocean hydro-thermodynamics equations and is nested in the basin-scale model of the Black Sea dynamics of Marine Hydrophysical Institute (Sevastopol). To solve the model equation system, a numerical algorithm based on the splitting method is used. Calculations show that circulation processes in the easternmost water area of the Black Sea are characterized by a permanent alternation of different circulation modes with the formation of mesoscale and submesoscale eddies throughout the year, which significantly affect the formation of thermohaline fields; atmospheric wind forcing substantially determines not only the peculiarities of the sea surface horizontal circulation, also the vertical structure of the current field.
... Water movements are regulated by the intensity and direction of winds (Barton et al., 2014) and circulations (e.g. rim current, mesoscale cyclonic and anticyclonic eddies, and coastal anticyclonic eddies) (Zatsepin et al., 2011;Kubryakov et al., 2012). Silkin et al. (2019) reported that seasonal dynamics of phytoplankton depends on inorganic nutrient concentrations in the NE Black Sea. ...
Phytoplankton size classes (PSCs) estimated by using high-performance liquid chromatography (HPLC) pigment data and pigment indices in the south-eastern Black Sea were used to characterise seasonal phytoplankton structure from November 2015 to August 2016. Results revealed significant seasonal variation in phytoplankton size classes hence community composition and pigment indices along the south-eastern Black Sea, varied from 2% to 71%; from 3% to 77%; from 5% and 91% for picophytoplankton, nanophytoplankton and microphytoplankton, respectively. Phytoplankton community composition was dominated by microphytoplankton with a high content of photosynthetic carotenoids. In-situ Chl-a concentrations changed during the study period, the highest concentration was detected in autumn (2.60 μg.l⁻¹) and spring (2.48 μg.l⁻¹). Pigment indices indicated that microphytoplankton carrying majority of photosynthetic carotenoids (PSCTP) dominated the community along the south-eastern Black Sea. PSCTP positively correlated with MicroDP, indicated that microphytoplankton seasonally optimise their light-harvesting capability along the south-eastern Black Sea. However, concomitant increase in PPCTPwith PicoDP and dominancy of PPCTP in summer indicated enhancing photoprotective carotenoid content during warm and nutrient depleted periods along the study area. Canonical correspondence analysis (CCA) explained general pattern of PSCs along the study area are controlled seasonally by physicochemical drivers (i.e. nutrient dynamics and pigment content). The differences detected phytoplankton community composition also indicated phytoplankton adaptive strategy to changing environmental factors.
... The RM-IG is the core of the regional forecasting system for the easternmost part of the Black Sea. The regional forecasting system is one of the components of the Black Sea basin-scale nowcasting/forecasting system [12]. ...
The study of water circulation and thermohaline processes in the coastal zones of the seas and oceans, subjected to the most intense anthropogenic press, is an important problem of modern Oceanology. According to experimental and theoretical researches the coastal water areas of the Black Sea are dynamically active regions, where intensive generation of mesoscale and submesoscale eddies takes place. Such eddies make a significant contribution to the horizontal and vertical transport of different polluting substances, heat, momentum, etc. Therefore, the modeling and study of main peculiarities of variability of regional dynamic processes is of great scientific and practical interest. The goal of this study is to investigate numerically the structure and spatial-temporal distribution of the sea flow and thermohaline fields taking place during the period 2017-2019 in the easternmost part of the Black Sea, which is limited from the open part of the sea basin with liquid boundary coinciding 39.08 0 E. With this purpose a high-resolution numerical regional model of the Black Sea dynamics of M. Nodia Institute of Geophysics of I. Javakhishvili Tbilisi State University (RM-IG) is used. The RM-IG is nested in the basin-scale model of the Black Sea dynamics of Marine Hydrophysical Institute (Sevastopol) and is based on a primitive system of ocean hydrothermodynamics equations. The RM-IG uses a calculated grid having 215x347 points on horizons with 1 km spatial resolution. Results of researches presented in the paper show significant variability of the regional dynamic processes in the easternmost water area during 2017-2019, where continuously generation, deformation and disappearance of the cyclonic and anticyclonic vortex formations of difference sizes takes place.
... Many observational programs help to understand the status of water quality and their trends which are more costly and time consuming. Hence a model based predication of water quality is more appraisable to acquire time series information spatio- Kubryakov et al., 2012). Operational systems developed to monitor and forecast water quality, can play a key role to achieve the health index of coastal any countries have their own of the sea to public and stakeholders through forecasting system. ...
Sujith Kumar, S.; Panda, U.S.; Pradhan, U.K; Mishra, P., and Ramana Murthy, M.V., 2020. Web-based decision support system for coastal water quality. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 139-144. Coconut Creek (Florida), ISSN 0749-0208.
Operational systems on real-time monitoring of coastal water quality can play a key role to counter and reduce the pollution causing hazardous events in the coastal region. An automated alert system is required to provide relevant information to the coastal authorities, water quality managers and other coastal stakeholders on a real-time basis to avoid any lead time or potential human errors. This paper presents an architecture for coastal water quality prediction and alert system by integrating different platforms and services to achieve scalability, provisioning of resources in real time, simplified deployment and management of resources and applications. The forecast system was developed through data assimilation from coupled hydrodynamic water quality models and field observations and archived in an integrated Database Management System (DBMS). A web-service is programmed to fetch the data from server on demand in order to disseminate the information to the public. Web applications use an architecture that breaks applications into discrete parts, using multiple programming languages and deploying the applications on several layers of technology. The other features of the website include Query builder as per user's specification, Fetch and display latest time series data on water quality parameters based on locations and graphical representation.
