Circulation of the Turkish Straits System under interannual atmospheric forcing

Aydoğdu, Ali; Pinardi, Nadia; Özsoy, Emi̇n; Danabasoglu, Gökhan; Gürses, Özgür; Karspeck, Alicia

doi:10.5194/os-14-999-2018

Cited by 27 publications

(24 citation statements)

References 52 publications

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“…Irrespective of the drawback, it can be said that the observed temperature profiles are modeled with a fair agreement. Along with the agreement of the model results and measurements, the salinity and temperature profiles are also accord with recent studies such as those of Sözer and Özsoy [30], Sannino et al [31], and Aydogdu et al [48]. Although these studies do not include modeling seasonal variations of salinity and temperature profiles, results regarding the stratification and density gradient phenomena are generally overlapping with the present study.…”

Section: Hydrographic Model Validationsupporting

confidence: 92%

Hydrodynamic and Hydrographic Modeling of Istanbul Strait

et al. 2019

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The aim of this study is to model the hydrodynamic processes of the Istanbul Strait with its stratified flow characteristics, and calibrate the most important parameters using local and global search algorithms. For that, two open boundary conditions are defined, which are in the northern and southern parts of the Strait. Observed bathymetric, hydrographic, meteorological, and water-level data are used to set up the Delft3D-FLOW model. First, the sensitivities of the model parameters on the numerical model outputs are assessed using Parameter EStimation Tool (PEST) toolbox. Then, the model is calibrated based on the objective functions, focusing on the flow rates of the upper and lower layers. The salinity and temperature profiles of the strait are only used for model validation. The results show that the calibrated model outputs of the Istanbul Strait are reliable and consistent with the in situ measurements. The sensitivity analysis reveals that the spatial low-pass filter coefficient, horizontal eddy viscosity, Prandtl–Schmidt number, slope in log–log spectrum, and Manning roughness coefficient are most sensitive parameters affecting the flow rate performance of the model. The agreement between observed salinity profiles and simulated model outputs is promising, whereas the match between observed and simulated temperature profiles is weak, showing that the model can be improved, particularly for simulating the mixing layer.

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Section: Hydrographic Model Validationsupporting

confidence: 92%

Hydrodynamic and Hydrographic Modeling of Istanbul Strait

et al. 2019

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“…In the BS-REA, a final correction, estimated from the CMEMS SSALTO/DUACS Delayed-Time Level-4 sea level anomalies measured by multi-satellite altimetry observations (Taburet et al, 2019), is applied to the freshwater balance at a single grid point adjacent to the Bosphorus Strait in order to impose the observed trend and variability in the mean sea surface height. T and S are relaxed toward a monthly climatological profile computed from a high-resolution multi-year simulation (Aydogdu et al, 2018), to properly represent the water mass properties exchanged between the Mediterranean and Black Seas via the Bosphorus Strait. This relaxation is applied at five grid points surrounding the location of the Bosphorus Strait with a time frequency of 1 hour.…”

Section: Ocean Modelmentioning

confidence: 99%

Climate Signals in the Black Sea From a Multidecadal Eddy-Resolving Reanalysis

et al. 2021

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Ocean reanalyses are becoming increasingly important to reconstruct and provide an overview of the ocean state from the past to the present-day. In this article, we present a Black Sea reanalysis covering the whole satellite altimetry era. In the scope of the Copernicus Marine Environment Monitoring Service, the Black Sea reanalysis system is produced using an advanced variational data assimilation method to combine the best available observations with a state-of-the-art ocean general circulation model. The hydrodynamical model is based on Nucleus for European Modeling of the Ocean, implemented for the Black Sea domain with a horizontal resolution of 1/27°× 1/36°, and 31 unevenly distributed vertical levels. The model is forced by the ECMWF ERA5 atmospheric reanalysis and climatological precipitation, whereas the sea surface temperature is relaxed to daily objective analysis fields. The model is online coupled to OceanVar, a 3D-Var ocean data assimilation scheme, to assimilate sea level anomaly along-track observations and in situ vertical profiles of temperature and salinity. Temperature fields present a continuous warming in the layer between 25 and 150 m, where the Black Sea Cold Intermediate Layer resides. This is an important signal of the Black Sea response to climate change. Sea surface temperature shows a basin-wide positive bias and the root mean square difference can reach 0.75°C along the Turkish coast in summer. The overall surface dynamic topography is well reproduced as well as the reanalysis can represent the main Black Sea circulation such as the Rim Current and the quasi-permanent anticyclonic Sevastopol and Batumi eddies. The system produces very accurate estimates of temperature, salinity and sea level which makes it suitable for understanding the Black Sea physical state in the last decades. Nevertheless, in order to improve the quality of the Black Sea reanalysis, new developments in ocean modeling and data assimilation are still important, and sustaining the Black Sea ocean observing system is crucial.

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“…Observations in the Marmara Sea have revealed two-layer stratified flow details, fluxes and circulation in this small internal sea (Ünlüata et al, 1990;Beşiktepe et al, 1993Beşiktepe et al, , 1994Özsoy et al, 2016), connected to the Black Sea and Aegean Sea, respectively, by the Bosphorus and Dardanelles straits.…”

Section: Interaction With Straitsmentioning

confidence: 99%

A model of Black Sea circulation with strait exchange (2008–2018)

Gündüz¹,

Özsoy

Hordoir

2020

Geosci. Model Dev.

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Abstract. The Bosphorus exchange is of critical importance for hydrodynamics and hydroclimatology of the Black Sea. In this study, we report on the development of a medium-resolution circulation model of the Black Sea, making use of surface atmospheric forcing with high space and time resolution, climatic river fluxes and strait exchange, enabled by adding elementary details of strait and coastal topography and seasonal hydrology specified in an artificial box on the Marmara Sea side. Particular attention is given to circulation, mixing and convective water mass formation processes in the model, which are then compared with observations. Open boundary conditions relaxed to seasonal hydrology specified in the artificial box are found to enable Bosphorus exchange with a proper upper layer, lower layer and net fluxes comparable to the observed ranges. These improvements at the artificial boundary and in the interior evolution of the Black Sea allow the study to capture daily, seasonal to decadal climatic variability and change observed in the Black Sea in the last few decades.

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Circulation of the Turkish Straits System under interannual atmospheric forcing

Cited by 27 publications

References 52 publications

Hydrodynamic and Hydrographic Modeling of Istanbul Strait

Hydrodynamic and Hydrographic Modeling of Istanbul Strait

Climate Signals in the Black Sea From a Multidecadal Eddy-Resolving Reanalysis

A model of Black Sea circulation with strait exchange (2008–2018)

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