scholarly journals Some aspects of the deep abyssal overflow between the middle and southern basins of the Caspian Sea

2017 ◽  
Author(s):  
Javad Babagoli Matikolaei ◽  
Abbas Ali AliAkbbari-Bidokhti ◽  
Maryam Shiea
Keyword(s):  
Caspian Sea ◽  
Dynamic Models ◽  
Gravity Current ◽  
Ocean Model ◽  
Density Difference ◽  
Dynamical Model ◽  
Western Coast ◽  
The Caspian Sea ◽  
Southern Basin ◽  
Simple Dynamical Model

Abstract. This study investigates the deep gravity current between the middle and southern Caspian Sea basins, caused by density difference of deep waters. Oceanographic data, numerical model and dynamic models are used to consider the structure of this Caspian Sea abyssal overflow. The CTD data are obtained from UNESCO, and the three-dimensional ocean model COHERENS results are used to study the abyssal currents in the southern basin of the Caspian Sea. The deep overflow is driven by the density difference mainly due to the temperature difference between the middle and southern basins especially in winter. For this reason, water sinks in high latitudes and after filling the middle basin it overflows into the southern basin. As the current passes through the Absheron Strait (or sill), we use an analytic model for the overflow gravity current with inertial and frictional effects to consider its structure. The dynamical characteristics of this deep baroclinic flow are investigated with different initial and boundary conditions. The results show that after time passes, the flow adjusts itself, moving as a deepening gravity driven topographically trapped current. This flow is considered for different seasons and its velocity and width are obtained. Because of the topography of the Southern Caspian basin, the flow is trapped after the sill; thus, another simple dynamical model of the overflow, based on potential vorticity conservation similar to that of Bidokhti and Ezam (2009) but with the bottom friction included, is used to find the horizontal extent of the outflow from the western coast. The result of this model shows that the Rossby length (deformation radius) of the flow decreases when drag coefficient increases. Because of the importance of the overflow in deep water ventilation, a simple dynamical model of the boundary currents based on the shape of strait is used to estimate typical mass transport and flushing time which is found to be about 15 to 20 years for the southern basin of the Caspian Sea. This time scale is important for the possible effects of pollutions due to oil exploration on the ecosystem of this water body.

scholarly journals Some aspects of the deep abyssal overflow between the middle and southern basins of the Caspian Sea

2018 ◽  
Author(s):  
Javad Babagoli Matikolaei ◽  
Abbasali Aliakbari Bidokhti ◽  
Maryam Shiea
Keyword(s):  
Potential Vorticity ◽  
Caspian Sea ◽  
Gravity Current ◽  
Bottom Friction ◽  
Density Difference ◽  
Dynamical Model ◽  
Western Coast ◽  
The Caspian Sea ◽  
Southern Basin ◽  
Simple Dynamical Model

Abstract. This study investigates the deep gravity current between the middle and southern Caspian Sea basins, caused by density difference of deep waters. Oceanographic data, numerical model and dynamic models are used to consider the structure of this Caspian Sea abyssal overflow. The CTD data are obtained from UNESCO, and the three-dimensional ocean model COHERENS results are used to study the abyssal currents in the southern basin of the Caspian Sea. The deep overflow is driven by the density difference mainly due to the temperature difference between the middle and southern basins especially in winter. For this reason, water sinks in high latitudes and after filling the middle basin it overflows into the southern basin. As the current passes through the Absheron Strait (or sill), we use an analytic model for the overflow gravity current with inertial effects, bottom friction and entrainment, to consider its structure. The dynamical characteristics of this deep baroclinic flow are investigated with different initial and boundary conditions. The results show that after time passes, the flow adjusts itself, moving as a deepening gravity driven topographically trapped current. This flow is considered for different seasons and its velocity and width are obtained. Because of the topography of the Southern Caspian basin, the flow is trapped after the sill; thus, another simple dynamical model of the overflow, based on potential vorticity similar to that of Bidokhti and Ezam (2009) but with the bottom friction and entrainment included, is used to find the horizontal extent of the outflow from the western coast. To estimate the changes of vorticity and potential vorticity of the flow over the Absheron sill, we use the method of Falcini and Salusti (2015), in this work, the effects of entrainment and friction are considered. Because of the importance of the overflow in deep water ventilation, a simple dynamical model of the boundary currents based on the shape of strait is used to estimate typical mass transport and flushing time which is found to be about 15 to 20 years for the southern basin of the Caspian Sea. This time scale is important for the possible effects on the ecosystem here of pollution due to oil exploration.

scholarly journals Some aspects of the deep abyssal overflow between the middle and southern basins of the Caspian Sea

Ocean Science ◽  
2019 ◽  
Vol 15 (2) ◽  
pp. 459-476
Author(s):  
Javad Babagoli Matikolaei ◽  
Abbasali Aliakbari Bidokhti ◽  
Maryam Shiea
Keyword(s):  
Caspian Sea ◽  
Oil Pollution ◽  
Gravity Current ◽  
Ocean Model ◽  
Density Difference ◽  
Cold Weather ◽  
The Caspian Sea ◽  
Southern Basin ◽  
Flushing Time ◽  
Southern Caspian Sea

Abstract. The present study investigates the deep gravity current between the middle and southern Caspian Sea basins caused by the density difference of deep waters. Oceanographic data, a numerical model and a dynamic model are used to consider the structure of this Caspian Sea abyssal overflow. The CTD data are obtained from UNESCO, and the three-dimensional COHERENS ocean model results are used to study the abyssal currents in the southern basin of the Caspian Sea. The deep overflow is driven by the density difference, which is mainly owing to the temperature difference, between the middle and southern basins, especially in winter. Due to cold weather in the northern basin, water sinks at high latitudes and after filling the middle basin it overflows into the southern basin. As the current passes through the Absheron Strait (or sill), we use the analytic model of Falcini and Salusti (2015) for the overflow gravity current to estimate the changes in the vorticity and potential vorticity of the flow over the Absheron sill; the effects of entrainment and friction are also considered. Due to the importance of the overflow with respect to deep water ventilation, a simple dynamical model of the boundary currents based on the shape of the Absheron Strait is used to estimate typical mass transport and flushing time; the flushing time is found to be about 15 to 20 years for the southern basin of the Caspian Sea. This timescale is important for the region's ecosystem and with respect to the impacts of pollution due to oil exploration. In addition, by reviewing the drilled oil and gas wells in the Caspian Sea, the results show that the deep overflow moves over some of these wells. Thus, the deep flow could be an important factor influencing oil pollution in the deeper region of the southern Caspian Sea.

On the type locality of the steppe ribbon racer, Psammophis lineolatus (Brandt, 1838) (Serpentes: Lamprophiidae)

2020 ◽  
Vol 324 (2) ◽  
pp. 262-272
Author(s):  
I.V. Doronin ◽  
T.N. Dujsebayeva ◽  
K.M. Akhmedenov ◽  
A.G. Bakiev ◽  
K.N. Plakhov
Keyword(s):  
Caspian Sea ◽  
Type Specimen ◽  
Type Locality ◽  
Eastern Coast ◽  
Zoological Museum ◽  
Western Coast ◽  
The Caspian Sea ◽  
Original Species ◽  
Academy Of Sciences ◽  
Made In

The article specifies the type locality of the Steppe Ribbon Racer. The holotype Coluber (Taphrometopon) lineolatus Brandt, 1838 is stored in the reptile collection of the Zoological Institute of the Russian Academy of Sciences (ZISP No 2042). Literature sources provide different information about the type locality. A mistake has been made in the title of the work with the original species description: the western coast of the sea was indicated instead of the eastern one. The place of capture was indicated as “M. Caspium” (Caspian Sea) on the label and in the reptile inventory book of the Zoological Museum of the Academy of Sciences. The specimen was sent to the museum by G.S. Karelin. The “1842” indicated on the labels and in the inventory book cannot be the year of capture of the type specimen, just as the “1837” indicated by A.M. Nikolsky. In 1837, Karelin was in Saint Petersburg and in 1842 in Siberia. Most likely, 1837 is the year when the collection arrived at the Museum, and 1842 is the year when the information about the specimen was recorded in the inventory book (catalog) of the Zoological Museum of the Academy of Sciences. In our opinion, the holotype was caught in 1932. From Karelin’s travel notes of the expedition to the Caspian Sea in 1832, follows that the snake was recorded in two regions adjacent to the eastern coast of the Caspian Sea – Ungoza Mountain (“Mangyshlak Mountains”) and site of the Western Chink of Ustyurt between Zhamanairakty and Kyzyltas Mountains (inclusive) on the northeast coast of Kaydak Sor (“Misty Mountains”). In our article, Karelin’s route to the northeastern coast of the Caspian Sea in 1832 and photographs of these localities are given. The type locality of Psammophis lineolatus (Brandt, 1838) should be restricted to the Mangystau Region of the Kazakhstan: Ungoza Mountain south of Sarytash Gulf, Mangystau (Mangyshlak) Penninsula (44°26´ N, 51°12´ E).

scholarly journals Numerical modelling of the Caspian Sea tides

Ocean Science ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 209-219
Author(s):  
Igor P. Medvedev ◽  
Evgueni A. Kulikov ◽  
Isaac V. Fine
Keyword(s):  
Caspian Sea ◽  
Ocean Model ◽  
Tidal Range ◽  
The South ◽  
Tidal Dynamics ◽  
The Caspian Sea ◽  
Sea Levels ◽  
The North ◽  
Anticlockwise Rotation ◽  
Diurnal Tides

Abstract. The Caspian Sea is the largest enclosed basin on Earth and a unique subject for the analysis of tidal dynamics. Tides in the basin are produced directly by the tide-generating forces. Using the Princeton Ocean Model (POM), we examine details of the spatial and temporal features of the tidal dynamics in the Caspian Sea. We present tidal charts of the amplitudes and phase lags of the major tidal constituents, together with maps of the form factor, tidal range, and tidal current speed. Semi-diurnal tides in the Caspian Sea are determined by a Taylor amphidromic system with anticlockwise rotation. The largest M2 amplitude is 6 cm and is located in Türkmen Aylagy (called Turkmen Bay hereafter). For the diurnal constituents, the Absheron Peninsula separates two individual amphidromes with anticlockwise rotation in the north and in the south. The maximum K1 amplitudes (up to 0.7–0.8 cm) are located in (1) the south-eastern part of the basin, (2) Türkmenbaşy Gulf, (3) Mangyshlak Bay; and (4) Kizlyar Bay. As a result, the semi-diurnal tides prevail over diurnal tides in the Caspian Sea. The maximum tidal range, of up to 21 cm, has been found in Turkmen Bay. The strongest tidal currents have been located in the straits to the north and south of Ogurja Ada, where speeds reach 22 and 19 cm s−1, respectively. Numerical simulations of the tides using different mean sea levels (within a range of 5 m) indicate that spatial features of the Caspian Sea tides are strongly sensitive to changes in mean sea level.

Numerical Study on Circulation and Thermohaline Structures With Effects of Icing Event in the Caspian Sea

2010 ◽  
Author(s):  
Daisuke Kitazawa ◽  
Jing Yang
Keyword(s):  
Numerical Simulation ◽  
Water Temperature ◽  
Coriolis Force ◽  
Caspian Sea ◽  
Numerical Study ◽  
Measurement Data ◽  
Ocean Model ◽  
Water Current ◽  
The Caspian Sea ◽  
Volga River

A hydrostatic and ice coupled model was developed to analyze circulation and thermohaline structures in the Caspian Sea. The northern part of the Caspian Sea freezes in the winter. Waters start icing in November and ices spread during December and January. The northern part of the Caspian Sea is covered by ices in severe winters. Ice-covered area is at its maximum during January and February, and then ices begin melting in March and disappear in April. The occurrence of ices must have significant effects on circulation and thermohaline structures as well as ecosystem in the northern Caspian Sea. In the present study, formation of ices is modeled assuming that ices do not move but spread and shrink on water surface. Under the ices, it is assumed that the exchange of momentum flux is impeded and the fluxes of heat and brine salt are given at sea-ice boundary. The ice model was coupled with a hydrostatic model based on MEC (Marine Environmental Committee) Ocean Model developed by the Japan Society of Naval Architect and Ocean Engineers. Numerical simulation was carried out for 20 years to achieve stable seasonal changes in current velocity, water temperature, and salinity. The fluxes of momentum, heat, and salt were estimated by using measurement data at 11 meteorological stations around the Caspian Sea. Inflow of Volga River was taken into account as representative of all the rivers which inflow into the Caspian Sea. Effects of icing event on circulation and thermohaline structures were discussed using the results of numerical simulation in the last year. As a result, the accuracy of predicting water temperature in the northern Caspian Sea was improved by taking the effects of icing event into account. Differences in density in the horizontal direction create several gyres with the effects of Coriolis force. The differences were caused by differences in heat capacity between coastal and open waters, differences in water temperature due to climate, and inflow of rivers in the northern Caspian Sea. The water current field in the Caspian Sea is formed by adding wind-driven current to the dominant density-driven current, which is based on horizontal differences in water temperature and salinity, and Coriolis force.

THE STUDY OF THE BIOLOGY OF THE ROACH RUTILUS RUTILUS CASPICUS (JAKOWLEV, 1870) IN THE KRAYNOVSKY COAST OF THE CASPIAN SEA

2021 ◽  
pp. 93-97
Author(s):  
Aysha Sh. Gasanova ◽  
Kais M. Guseynov ◽  
Ruslan M. Barkhalov ◽  
Marina V. Khlopkova
Keyword(s):  
Caspian Sea ◽  
Rutilus Rutilus ◽  
Western Coast ◽  
The Caspian Sea ◽  
Roach Rutilus Rutilus ◽  
River Fish

The offshore zone of the western coast of the Caspian Sea is one of the most highly productive. Of the 63 species of fish that live in the Caspian Sea, 34 species are found on the Krainovsky coast, 42 % of which are carp. The most numerous is the roach Rutilus rutilus caspicus (Jakowlev, 1870), which makes up 50–86 % of the number of semi-passerine and river fish. The article presents the results of studies of the peculiarities of the biology of the roach Rutilus rutilus caspicus of the Krainovsky coast of the Caspian Sea. The roach is noted in the catches constantly. Her age in the networks ranges from 2 to 10 years. The share of 3-5-year-olds accounts for 81 %. Females in catches make up 66 %, males - 34 %. The parameters of the Bertalanfi equation are characterized by the following values: L =38.8 cm, K = 0.12, t° = -2.67. The fecundity of the roach on average is 30.2 thousand eggs and tends to increase with increasing length and weight of the fish. As the roach grows, the composition of its food changes significantly. The maximum fed roach length from 10 to 20 cm.

scholarly journals THE OVCHULAR SHELTER ON THE UPPER TERRACE OF MOUNTAIN BEYUKDASH

2019 ◽  
Vol 15 (3) ◽  
pp. 471-485
Author(s):  
Malahat N. Farajova
Keyword(s):  
Bronze Age ◽  
Caspian Sea ◽  
Western Coast ◽  
The Caspian Sea ◽  
Archaeological Data ◽  
Important Challenge ◽  
Field Works ◽  
Historical Periods ◽  
The Bronze Age ◽  
Geological Research

Gobustan is a rich archaeological area where people lived at different period, thousands of rock paintings, dozens of sites, settlements, tombs and other monuments of different historical periods have preserved. Ovchular shelter takes a special place among these caves, which is date back to the Stone and Bronze ages, approximately before VI-IV Millenniums B.C. according to some archeologists. Hence, the question of study of rock images of this complex with using geological and archaeological data for reconstruction the archaeological landscape of upper terrace of Boyukdash Mountain is extremely important challenge.  The archaeologists Dj. Russtamov and F. Muradova started first field works in the Ovchular cave. On the walls of the cave displayed hunting scenes, battle, ritual dances. Discovered archaeological artefacts and images by archaeologists show that habitat indications of human in the cave presumably date back to the period of domestication of animals. During field works for night photography in 2004 here were discovered new petroglyphs – 2 figures of ibexes. A special interest represent dotted recesses engraved under one figure of animal.  No doubt that this cave used for specific rituals and magic procedures. Archaeologists date back this shelter by the period of transition from the Mesolithic to Neolithic. Discovered fragments of vessel from mixed coarse clay let researchers suppose about settling of this cave in the Bronze Age also. As a result of geological research in the western coast of the Caspian Sea, it was also possible to determine the transgression which observed 6 thousand years ago, and the beginning of  regression which observed 4 thousand years ago ,so the retreat of the sea. Thus, while the lower terraces of  Boyukdash mountain  were periodically washed by the historical Caspian Sea and  could not reach to the upper terraces, in particular, to the Ovchular site.

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