Study of water exchange in Kerch strait using NEMO model of Black Sea

2021 ◽  
Author(s):  
Roman Sedakov ◽  
Barnier Bernard ◽  
Jean-Marc Molines ◽  
Anastasiya Mershavka
Keyword(s):  
Water Flow ◽  
Black Sea ◽  
Water Exchange ◽  
Discharge Rate ◽  
The Black Sea ◽  
External Forcing ◽  
Sea Of Azov ◽  
The Sea Of Azov ◽  
The North ◽  
Kerch Strait

<p>The Sea of Azov is a small, shallow, and freshened sea that receives a large freshwater discharge. Under certain external forcing conditions brackish water from the Sea of Azov flow into the north-eastern part of the Black Sea through the narrow Kerch Strait and form a surface-advected buoyant plume. Water flow in the Kerch Strait also regularly occurs in the opposite direction, which results in the spreading of an advected plume of saline and dense water from the Black Sea into the Sea of Azov. Using a regional Black Sea Azov Sea model based on NEMO we study physical mechanisms that govern water exchange through the Kerch Strait and analyze the dependence of its direction and intensity on external forcing conditions. We show that water exchange in the Kerch Strait is governed by a wind-induced barotropic pressure gradient. Water flow through the shallow and narrow Kerch Strait is a one-way process for the majority of the time. Outflow from the Sea of Azov to the Black Sea is induced by moderate and strong northerly winds, while flow into the Sea of Azov from the Black Sea is induced by southerly winds. The direction and intensity of water exchange have wind-governed synoptic and seasonal variability, and they do not depend on the variability of river discharge rate to the Sea of Azov on an intraannual timescale.</p>

scholarly journals Water exchange between the Sea of Azov and the Black Sea through the Kerch Strait

Ocean Science ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Ivan Zavialov ◽  
Alexander Osadchiev ◽  
Roman Sedakov ◽  
Bernard Barnier ◽  
Jean-Marc Molines ◽  
...  
Keyword(s):  
Water Flow ◽  
Black Sea ◽  
Water Exchange ◽  
The Black Sea ◽  
External Forcing ◽  
Sea Of Azov ◽  
Buoyant Plume ◽  
The Sea Of Azov ◽  
The North ◽  
Kerch Strait

Abstract. The Sea of Azov is a small, shallow, and freshened sea that receives a large freshwater discharge. Under certain external forcing conditions low-salinity waters from the Sea of Azov flow into the north-eastern part of the Black Sea through the narrow Kerch Strait and form a surface-advected buoyant plume. Water flow in the Kerch Strait also regularly occurs in the opposite direction, which results in the spreading of a bottom-advected plume of saline and dense waters from the Black Sea into the Sea of Azov. In this study we focus on the physical mechanisms that govern water exchange through the Kerch Strait and analyse the dependence of its direction and intensity on external forcing conditions. Analysis of satellite imagery, wind data, and numerical modelling shows that water exchange in the Kerch Strait is governed by a wind-induced barotropic pressure gradient. Water flow through the shallow and narrow Kerch Strait is a one-way process for the majority of the time. Outflow from the Sea of Azov to the Black Sea is induced by moderate and strong north-easterly winds, while flow into the Sea of Azov from the Black Sea occurs during wind relaxation periods. The direction and intensity of water exchange have wind-governed synoptic and seasonal variability, and they do not depend on the rate of river discharge to the Sea of Azov on an intra-annual timescale. The analysed data reveal dependencies between wind forcing conditions and spatial characteristics of the buoyant plume formed by the outflow from the Sea of Azov.

scholarly journals Water exchange between the Sea of Azov and the Black Sea through the Kerch Strait

2019 ◽  
Author(s):  
Ivan Zavialov ◽  
Alexander Osadchiev
Keyword(s):  
Water Transport ◽  
Black Sea ◽  
Opposite Direction ◽  
Water Exchange ◽  
Discharge Rate ◽  
The Black Sea ◽  
External Forcing ◽  
Sea Of Azov ◽  
The Sea Of Azov ◽  
Kerch Strait

Abstract. The Sea of Azov is a small, shallow and freshened sea that receives a large freshwater discharge and, therefore, can be regarded as a large river estuary. Under certain external forcing conditions low-saline waters from the Sea of Azov inflow to the northeastern part of the Black Sea through the narrow Kerch Strait and form a surface-advected buoyant plume. Water flow in the Kerch Strait also regularly occurs in the opposite direction, which results in spreading of a bottom-advected plume of saline and dense waters from the Black Sea in the Sea of Azov. In this study we focus on physical mechanisms that govern water exchange through the Kerch Strait, analyse dependence of its direction and intensity on external forcing conditions. Based on ocean color satellite imagery and wind reanalysis data, we show that water transport from the Sea of Azov to the Black Sea is induced by moderate and strong northeastern winds, while water transport in the opposite direction occurs during wind relaxation periods. Thus, direction and intensity of water exchange through the Kerch Strait has wind-govern synoptic and seasonal variability, and do not show dependence on river discharge rate to the Sea of Azov on intra-annual time scale. Finally, we determined numerical dependencies between discharge rate from the Sea of Azov to the Black Sea and spatial characteristics of the related surface-advected plume in the Black Sea, on the one hand, and wind forcing conditions, on the other hand.

Results of Monitoring of Temperature Conditions of Migration and Fishing of the Azov Khamsa

2020 ◽  
pp. 71-77
Author(s):  
Boris N. Panov ◽  
Elena O. Spiridonova ◽  
Michail M. Pyatinskiy ◽  
Aleksandr S. Arutyunyan
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Water Temperature ◽  
Black Sea ◽  
Sea Surface ◽  
The Black Sea ◽  
Sea Of Azov ◽  
The Sea Of Azov ◽  
Kerch Strait ◽  
Flood Zone

The paper presents the results of monitoring the process of migration and fishing of the Azov khamsa in April-May and October-November, 2019. The research used daily maps of sea surface temperature (SST) of the Black and Azov seas, built in the hydrometeorological Center of Russia according to NCDC/NOAA (Operational module Yessim - hmc.meteorf.ru/sea/black/sst/sst_black.htm) and daily fishing information of the Center for Monitoring of Fisheries and Communications. It is shown that in the spring, khamsa clusters begin to disperse and move to feeding places after the water temperature reaches 11 °C, and at a water temperature of 14-15 °C, the fish becomes much more mobile and the clusters finally disperse. In autumn, the Azov khamsa began to concentrate in the pre-flood zone of the Sea of Azov at an average SST of 16-17 °C, with a SST of 14-16 °C, the khamsa went out into the Kerch Strait. The active output of the khamsa into the Black Sea began at the SST of the pre-flood zone of 15 °C and almost stopped at the SST of about 13 °C. The average SST in the Kerch Strait dropped to 11 °C these days.

Plastic debris and plastic litter in the Kerch Strait of the Black Sea

2021 ◽  
Author(s):  
Peter Zavialov
Keyword(s):  
Cross Section ◽  
Black Sea ◽  
The Black Sea ◽  
Average Weight ◽  
Large Set ◽  
Sea Of Azov ◽  
Shirshov Institute ◽  
The Sea Of Azov ◽  
Kerch Strait ◽  
The Cross

<p>It is well-known that the shallow Sea of Azov can be thought of as a large estuary receiving discharges from the Don and the Kuban rivers, therefore, the flow through the Kerch Strait towards the Black Sea usually carries a variety of pollutants. However, the flux of plastic waste through the Strait has never been quantified. In situ measurements and sampling of microplastic debris and floating plastic litter in the Kerch Strait were conducted by a team from Shirshov Institute of Oceanology on July 16-18, 2020, along with CTD and ADCP profiling in the cross-section of the strait. The microplastic debris were sampled using a 0.3 mm mesh size Manta trawl net towed behind the R/V "Peleng" cruising at 4 kts and taking material from the upper 1 m of the water column. As a result, a large set of plastic particles, fibers and films were collected. All sampled items were measured, weighted, and sorted by composition using Micro NIR 1700 spectrometer instrument. The particle sizes ranged from 0.4 to 25.0 mm and weights varied between 0.05 and 7.72 mg. With respect to the chemical composition, about 63% of the collected particles were udentified as HDPE (high-densuty polyethylene), 21% as PP (polypropylene), 5% as PET (polyethylene terephthalate), 4% as PA (polyamide), 4% as PC (polycarbonate), and 3% as all other types of plastic. The content of visually identifiable plastic litter in the Kerch Strait varied between about 10 and 200 pieces per km<sup>2</sup>, with the average value close to 100 pieces/km<sup>2</sup>. However, the distribution was far from homogeneous – the litter was mainly concentrated in the western part of the Strait, where the principal stream carrying the Sea of Azov water into the Black Sea is usually localized. The newly obtained data of plastic litter concentration together with the current velocity data collected in ADCP profiling enabled us to estimate for the first time the flux of plastic through the Kerch Strait from the Sea of Azov into the Black Sea. This can be done by simply multiplying the plastic concentration by the velocity and then integrating it over the cross-section of the Strait. This procedure yields an estimate of 14,700 major pieces of plastic such as bottles, bags, etc., passing through the Strait per day. Assuming the average weight of a plastic litter piece 15 g , this leads to 220 kg/day, or about 9 kg/hour. This is quite a considerable mass of plastic, although it is about 20 times smaller than the amount brought to the Black Sea by the Danube according to [Lechner et al., 2014]. It must be kept in mind, however, that our estimate for the Kerch Strait is based on instantaneous one-time measurements, and may not represent long-term average values.</p><p>The studies described in this presentation represent the Russian contribution to the PLUMPLAS Project within STI BRICS cooperative initiative, implemented through the Russian Basic Research Foundation grant 19-55-80004.</p>

scholarly journals Results of adaptation and verification of the coupled numerical models set for predicting the variation of oceanographic features in the North-Western part of the Black Sea

2019 ◽  
pp. 95-108
Author(s):  
D. V. Kushnir ◽  
Yu. S. Tuchkovenko ◽  
Yu. I. Popov
Keyword(s):  
Wind Speed ◽  
Black Sea ◽  
Numerical Models ◽  
Forecast Model ◽  
The Black Sea ◽  
Sea Of Azov ◽  
The Sea Of Azov ◽  
The North ◽  
Operational Forecasting ◽  
North Western

In 2014 Ukraine lost the Ukrainian National Automated System of Marine Forecasting for the Black Sea that was created and operated at the premises of Marine Hydrophysical Institute of the National Academy of Sciences of Ukraine located in the Crimea. Within the framework of research works aimed at establishing a new marine forecasting system a possibility of employing the internationally acclaimed set of coupled numerical models Delft3D-FLOW + SWAN (the Simulating WAves Nearshore) for operational forecasting of the short-term (5 to 10 days) spatio-temporal variability of oceanographic features in the Ukrainian part of the Sea of Azov and the Black Sea Basin is considered. To ensure operation of the models set in the forecasting mode it was suggested to use a prediction of variability of meteorological characteristics at the air-sea interface obtained with the help of the numerical weather forecast model GFS (Global Forecast System). This paper presents the results of verification of Delft3D-FLOW and SWAN numerical models which were adapted to the conditions of the North-Western part of the Black Sea and its Odesa area in the version of meteorological data (fields of wind speed and direction, atmospheric pressure) assimilation from the GFS forecast archive. A technique of telescoping the spatial curvilinear computational grids with different resolution capacity was used in the process of models set adaptation to the conditions of the prognostic area. The models were verified by comparing modelling results with observational data on sea level variability in the ports of Odesa area of the North-Western part of the Black Sea (Chornomorsk, Odesa, Yuzhnyi), as well as with data on wind speed and direction, drift currents and characteristics of wind-induced waves recorded over the studied periods by the gauges of stationary hydrometeorological buoy which was mounted in the Bay of Odessa. Based on the analysis of the results of verification of coupled numerical models Delft3D-FLOW + SWAN set it was concluded that the set of coupled models has good prospects of being used in the system of operational forecasting of the variability of oceanographic parameters of the sea environment in the Ukrainian part of the Sea of Azov and the Black Sea Basin in the version of assimilation of meteorological information obtained from the GFS global forecast model.

scholarly journals Differences In Skull Size Of Harbour Porpoises, Phocoena phocoena (Cetacea), In The Sea Of Azov And The Black Sea: Evidence For Different Morphotypes And Populations

2015 ◽  
Vol 49 (2) ◽  
pp. 171-180 ◽  
Author(s):  
P. E. Goldin ◽  
K. A. Vishnyakova
Keyword(s):  
Black Sea ◽  
The Black Sea ◽  
Sea Of Azov ◽  
Phocoena Phocoena ◽  
The Sea Of Azov ◽  
Skull Size ◽  
The North ◽  
North Eastern ◽  
The Difference ◽  
North Western

Abstract There are two porpoise stocks in the northern Black Sea: the north-western (Odessa Gulf) and northeastern (Crimean and Caucasian waters); in addition, another stock is in the Sea of Azov. The Azov porpoises are distinct in their body size and biology. This research was conducted on the skulls of stranded sexually mature porpoises from the north-eastern Black Sea, north-western Black Sea and the Sea of Azov. In the north-eastern Black Sea samples, both present-day and old-time, the sexual dimorphism of the skull size was not significant, whereas in the Sea of Azov the females were significantly larger than males. The Azov skulls were strongly different from those from the Black Sea: they were larger, proportionally wider and had the wider rostra; also, there was no significant chronological variation within the Black Sea. The Azov and Black Sea samples were classified with the 100 % success with four variables. The northwestern Black Sea skulls were somewhat intermediate in their characteristics between the Azov and northeastern Black Sea samples, but they were classify ed together with other Black Sea specimens. The difference between the Azov and Black Sea skulls was greater than between many North Atlantic populations, despite the extreme geographical proximity of the two stocks. The low variation within the Black Sea supports the earlier conclusions on the lack of genetic variation: all the Black Sea stocks are expected to be genetically similar sub-populations, whereas the Azov and Marmara stocks possibly represent the genetically distant populations. The porpoises from the Black Sea and the Sea of Azov equally show the traits which characterize the subspecies Phocoena phocoena relicta, but the Black Sea porpoises appear to be more paedomorphic in terms of ontogenetic trajectories.

scholarly journals Microalgae of mud volcano of the Bulganak sopochnoe field on the Crimean Peninsula

2020 ◽  
Vol 5 (1) ◽  
pp. 64-77
Author(s):  
L. I. Ryabushko ◽  
A. V. Bondarenko
Keyword(s):  
Species Composition ◽  
Black Sea ◽  
Brackish Water ◽  
Mud Volcano ◽  
General Distribution ◽  
The Black Sea ◽  
Sea Of Azov ◽  
Mud Volcanoes ◽  
The Sea Of Azov ◽  
The World

Mud volcanoes are one of unique natural phenomena widely spread around the world. They can be found in Crimea, including the Bulganak sopochnoe field – the largest cluster of active mud volcanoes on the peninsula (45°25′29.04″N, 36°27′51.64″E). Study of mud volcano microalgae in Crimea, as well as in other regions of Russia, has not been conducted so far. Therefore, scientific interest is caused by need and urgency of the study of these volcanoes. First data on microalgae species composition of active mud volcanoes are presented in this article. Samples collected by O. Yu. Eremin (03.08.2012 and 13.04.2013) in the upper 2–3-cm layer of suspension and in surface water were investigated. The ranges of salinity and water temperature were 27–32 g per L and +28…+31 °C, respectively. Microalgae species composition was determined in water preparations using Axioskop 40 (Carl Zeiss) light microscope at magnification of 10×40 with software AxioVision Rel. 4.6. Totally 16 taxa were found: Cyanobacteria (1), Dinophyta (2), Bacillariophyta (6), and Euglenophyta (7). Of these, cyanobacteria Chamaecalyx swirenkoi (Schirshov) Komárek et Anagnostidis, 1986 was found by us in the mud volcano in August 2012. Pennate species of diatoms were also identified – single living (of genera Cylindrotheca (Ehrenberg) Reimann & J. C. Lewin, Lyrella Karajeva, and Nitzschia Hassall) and colonial species (of genera Berkeleya Greville and Pseudo-nitzschia H. Peragallo). The brackish-water, benthic, boreal-tropical species Nitzschia thermaloides Hustedt was recorded for the algal flora of Crimea, the Black Sea, and the Sea of Azov for the first time. Euglenophytes were also found in the samples – 5 species of the genus Trachelomonas Ehrenberg and 2 species of the genus Strombomonas Deflandre. Of all the species found in the mud volcano ecotope, 7 species are common for the Black Sea, and 9 species, including 3 euglenophytes, are common for the Sea of Azov. It is shown that by characteristics of halobility, species found in the mud volcano belong to freshwater complex (53 %), with a significant share of marine (27 %) and brackish-water (20 %) species. Of the phytogeographic flora elements, boreal species make up 33 %, boreal-tropical – 47 %, and cosmopolites – 20 %. Three species of potentially toxic algae are recorded: diatom Pseudo-nitzschia prolongatoides (Hasle) Hasle, 1993, as well as dinophytes Prorocentrum lima (Ehrenberg) Dodge, 1975 and Alexandrium tamiyavanichii Balech, 1994. The last species is marine, boreal-tropical, and new to the algology of Crimea, the Black Sea, and the Sea of Azov. In the article, own and literary data on morphology, ecology, and phytogeography of species, as well as on their general distribution in different waterbodies of the world, are also presented. Some microalgae species are indicators of saprobity; they are able to participate in purification of water from organic substances. Photos of mud volcanoes and micrographs of some species are presented.

Organic Matter of Bottom Sediments of the Crimean and Caucasian Coasts (Azov and Black Seas)

2021 ◽  
Author(s):  
E. A. Tikhonova ◽  
Keyword(s):  
Organic Matter ◽  
Black Sea ◽  
Bottom Sediments ◽  
Petroleum Hydrocarbons ◽  
Water Area ◽  
The Black Sea ◽  
Pollution Level ◽  
Sea Of Azov ◽  
The Caucasus ◽  
The Sea Of Azov

As part of the 113th cruise of the R/V “Professor Vodyanitsky”, research was conducted on organic pollution of bottom sediments in the coastal areas of Crimea and the Caucasus, as well as the water area in front of the Kerch Strait. Concentration of chloroformextractable substances was determined by the weight method and that of petroleum hydrocarbons was determined using infrared spectrometry. Both in 2020 and 2016 (the 83d cruise of the R/V “Professor Vodyanitsky”), properties of the bottom sediments of the Crimean and Caucasian coasts were typical of the marine soils of this region. This indicates that the studied water areas are generally in good condition. In accordance with the regional classification of bottom sediment pollution, the maximum concentrations of chloroform-extractable substances obtained for both the Black Sea and the Sea of Azov coast indicate pollution level III (23% of analysed samples). These values were found in bottom sediments in the Sevastopol water area (225 mg·100 g-1), in the coastal area of Cape Tarkhankut (120 mg·100 g-1) and Karadag (120 mg·100 g-1), the southern part of the Sea of Azov (125 mg·100 g-1) and Tuapse (110 mg·100 g-1). The content of chloroform-extractable substances in bottom sediments off the Black Sea coast of the Caucasus and the Sea of Azov coast is slightly lower than that off the Crimean coast. Pollution level II is assigned to bottom sediments in 46 % of the samples, with an average concentration of 72 mg·100 g-1 of air-dry solids. The rest (31 %) of the studied area was classified as conditionally clean (pollution level I, i. e. less than 50 mg·100 g-1). There has been a slight increase in the concentration of petroleum hydrocarbons in the bottom sediments of both the Black Sea and the Sea of Azov and their share in the total amount of chloroformextractable substances. In general, the level of pollution of bottom sediments by organic matter remained unchanged if compared with previous years, in particular with the data from 2016

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