Application of a three-dimensional numerical model to the idealized conditions of the bosphorus strait.

Sözer, Adil
The Bosphorus Strait is a narrow and shallow channel between the Sea of Marmara and the Black Sea which plays an important role in the Turkish Straits System connecting the Black Sea and the Mediterranean Sea. The exchange flow through the Bosphorus Strait is principally determined by geometry and stratification, and exhibits a complex nonlinear response to forcing by the net water budget, pressure and wind setup effects in adjacent basins. This study aims for a better understanding of the behaviour of the Bospho rus Strait flow, based on a three-dimensional model of its idealized dynam ics. The response of the Strait is investigated with respect to open boundary conditions corresponding to idealized geometrical and hydrographical condi tions. Although the rigid-lid assumption would be appropriate for long-term dynamics, a model with free-surface was used to predict short-term changes and relate them to sea-level variability in the Strait and the adjacent basins. The free-surface, primitive equation model, SCRUM, was used for numerical simulations. The model has terrain-following coordinates, optional mixing iiiparametrizations, and various choices for the bottom, solid or open boundary conditions. Many simulations were performed including the testing of boundary con ditions, experiments with different types of horizontal and vertical mixing and diffusion parametrizations, advection schemes and tests of geometrical effects as well as grid type and the resolution. These results were compared with two-layer analytical solutions of exchange flows and the observations in the Bosphorus. These simulations showed the three-dimensional model to be applicable to the special case of strait exchange flows. The selection of the open boundary conditions is a non-trivial first step for successful application of the model. The results obtained from the tests with idealized cases corresponding to the Bosphorus Strait indicate the need for judicious choices of open boundary conditions, which depend on the flow direction. The results obtained with these choices and even the case with pure radiation boundary conditions started from 'lock-exchange' initial condition, support the existence of max imal exchange type of controlled flows, exemplified by observations in the Bosphorus. With guidance of the results obtained from applications to idealized cases, the model was succesfully implemented to the actual geometrical and to pographical conditions of the Bosphorus Strait, although conclusive results could not yet be obtained. A very encouraging point has been reached for further investigations which are needed on tuning of the model parameters to obtain realistic results consistent with observations in the Bosphorus Strait.


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The Bosphorus is oceanographically very complicated two-layer stratified strait where denser water from the Marmara Sea flows towards North under the lighter water which is frequently flowing from the Black Sea towards South. The water level difference between both ends of the Bosphorus varies seasonally within the range of -0.2 and 0.6 m. The seasonal variability depends mainly on the water level changes in the adjacent basins related to the hydrological cycle, short-term changes in the atmospheric pressur...
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Tsunami hazard assessment of the eastern part of the Mediterranean Sea is the current interest of the countries having, a coastline in this region. Considering today's increasing population on the coasts and historical tsunamis, it is essential to estimate the probable tsunami risk, which might occur, to be able to mitigate the risk before the actual tsunami event happens. For this purpose, European Union funded project., SEAHELLARC is formed to develop a methodology and tools for seismic and tsunami safety...
Water Exchange through Canal İstanbul and Bosphorus Strait
Sözer, Adil; Ozsoy, E. (National Documentation Centre (EKT), 2017-2-13)
The Turkish Straits System (TSS) regulates the transports of water, material and energy between the Black Sea and the Mediterranean Sea. Amidst existing environmental threats to the region surrounding I.stanbul, the environmental footprint of the proposed Canal I.stanbul project needs to be evaluated through methods of natural science. We take the elementary step to answer the particular problem of coupled strait dynamics by adding the Canal to an existing hydrodynamic model and estimate changes in their co...
Copepod communities, production and grazing in the Turkish Straits System and the adjacent northern Aegean Sea during spring
Zervoudaki, S.; Christou, E. D.; Assimakopoulou, G.; Orek, H.; Gücü, Ali Cemal; Giannakourou, A.; Pitta, P.; TERBIYIK KURT, TUBA; Yucel, N.; Moutsopoulos, T.; Pagou, K.; Psarra, S.; Ozsoy, E.; Papathanassiou, E. (2011-06-01)
The Mediterranean and the Black Seas are connected through Bosphorus, Marmara Sea and Dardanelles (Turkish Straits System, TSS). In this study, we examined the spatial distribution of copepods and investigate their production and grazing. The aim was to understand the transfer of phytoplankton/microzooplankton production up the food chain in TSS and Aegean Sea during spring. The phytoplankton and microzooplankton biomass and production showed a clear decreasing trend from Bosphorus to the Aegean Sea, wherea...
The distribution of man-made and naturally produced halocarbons in a double layer flow strait system
Fogelqvist, E; Tanhua, T; Basturk, O; Salihoglu, I (1996-08-01)
The Bosphorus Strait, which connects the Black Sea and Mediterranean Sea via the Marmara Sea, is characterised by two distinct water masses. The upper layer consists of low density Black Sea water (sigma-t 10-11) flowing southward, and it is underlain by high density water (sigma-t > 28) of Mediterranean origin flowing northward. The sharp density gradient between the two layers is due to the difference in salinities. Here we report measurements on a suite of low molecular weight halocarbons together with b...
Citation Formats
A. Sözer, “Application of a three-dimensional numerical model to the idealized conditions of the bosphorus strait.,” Middle East Technical University, 2002.