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.

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.

X. Growing Tension and the Threat of War in the Southern Caspian Sea: The Unsettled Division Dispute and Regional Rivalry

2003 ◽  
Vol 2 (3) ◽  
pp. 575-591
Author(s):  
Hooman Peimani
Keyword(s):  
Caspian Sea ◽  
The United States ◽  
Caspian Region ◽  
Legal Regime ◽  
The Caspian Sea ◽  
Military Conflict ◽  
American Military ◽  
Military Presence ◽  
Military Conflicts ◽  
Southern Caspian Sea

AbstractThe absence of an acceptable legal regime for the division of the Caspian Sea among its five littoral states has created grounds for conflicts, crises, and wars in the Caspian region, a situation worsened since 2001 when Iran, Azerbaijan, and Turkmenistan found each other on a collision course over the ownership of certain offshore oilfields. The region has since been heading towards militarization, while the persistence of conflicts over the Caspian Sea's division has prepared the ground for military conflicts. Fear of lagging behind in an arms and the manipulation of conflicts by the United States and Turkey have further encouraged militarization. Against this background, certain factors, including Turkey's efforts to deny Iran political and economic gains in the Caspian region, the growing American military presence in Eurasia, and the expanding American-Azeri military ties since 11 September 2001 will likely contribute to the creation of a suitable ground for a military conflict in the Caspian region.

Paracobitis abrishamchiani, a new crested loach from the southern Caspian Sea basin (Teleostei: Nemacheilidae)

Zootaxa ◽  
2019 ◽  
Vol 4545 (3) ◽  
pp. 375 ◽  
Author(s):  
HAMED MOUSAVI-SABET ◽  
SABER VATANDOUST ◽  
MATTHIAS F. GEIGER ◽  
JÖRG FREYHOF
Keyword(s):  
New Species ◽  
Middle East ◽  
Caspian Sea ◽  
Colour Pattern ◽  
Nucleotide Substitutions ◽  
The Caspian Sea ◽  
Dorsal Fin ◽  
Mtdna Coi ◽  
River Drainages ◽  
Southern Caspian Sea

Paracobitis abrishamchiani, new species, is described from the southern Caspian Sea basin, where it is found in the Babol, Haraz, Siah, Tajan, Talar and Kashpal River drainages. It is distinguished from P. hircanica and P. atrakensis, the two other Paracobitis species known from the Caspian Sea basin, by having scales on the flank posterior to the dorsal-fin origin and from its congeners in the Middle East by the position of its dorsal-fin origin, having a roundish posterior narial opening, and a colour pattern consisting of many widely spaced brown spots and blotches. It is further characterized by six diagnostic nucleotide substitutions and a minimum K2P distance of 4.3% to P. persa and 4.6% to P. malapterura in the mtDNA COI barcode region. 

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.

Oil pollution in the Caspian Sea coastal waters

2006 ◽  
Vol 26 (4) ◽  
pp. 347
Author(s):  
Ahmad Khatoonabadai ◽  
Ahmadreza R. Mohammadi Dehcheshmeh
Keyword(s):  
Coastal Waters ◽  
Caspian Sea ◽  
Oil Pollution ◽  
The Caspian Sea

scholarly journals THE INFLUENCE OF OIL PRODUCTION ON AQUATIC ORGANISMS OF THE CASPIAN SEA

2019 ◽  
pp. 6-10
Author(s):  
Marina Vladimirovna KHLOPKOVA
Keyword(s):  
Invasive Species ◽  
Species Composition ◽  
Caspian Sea ◽  
Oil Pollution ◽  
Aquatic Organisms ◽  
Oil Production ◽  
Oil Products ◽  
Drilling Fluids ◽  
The Caspian Sea

The article summarizes data on the effects of oil products and drilling fluids on the inhabitants of the Caspian Sea., Compared to the Caspian autochthons, invasive species are more resistant to oil pollution. It leads to changes in the species composition of the biocenoses.

scholarly journals The first evidence for Late Pleistocene hominin populations on the southern Caspian Sea coast

Antiquity ◽  
2017 ◽  
Vol 91 (355) ◽  
Author(s):  
Hamed Vahdati Nasab ◽  
Kourosh Roustaei ◽  
Mohammad Ghamari Fatideh ◽  
Fatemeh Shojaeefar ◽  
Milad Hashemi Sarvandi
Keyword(s):  
Water Resources ◽  
Late Pleistocene ◽  
Caspian Sea ◽  
Climatic Conditions ◽  
Human Settlement ◽  
The Caspian Sea ◽  
The North ◽  
Dispersal Corridors ◽  
Sea Coast ◽  
Southern Caspian Sea

The southern shore of the Caspian Sea is well known for its great potential in relation to sites of Mesolithic date (e.g. Coon 1951; Jayez & Vahdati Nasab 2016). Situated between two major geographic barriers—the Alborz Mountains to the south, and the Caspian Sea to the north—this area has been considered one of the major hominin dispersal corridors during the Pleistocene–Holocene transition (Vahdati Nasab et al. 2013). Furthermore, the relatively stable and mild climatic conditions, vast and lush temperate forests, and abundance of fauna and water resources have all made this region an attractive niche for human settlement.

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