Control of Black Sea intermediate water mass formation by dynamics and topography: Comparison of numerical simulations, surveys and satellite data

Stanev, Emil V.; Bowman, Malcolm J.; Peneva, Elisaveta; Staneva, Joanna

doi:10.1357/002224003321586417

Cited by 57 publications

(99 citation statements)

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“…Two Argo floats were deployed on 7 May 2010 in the northern Black Sea (Stanev et al, 2013). The floats known as the Navigating European Marine Observer (NEMO) profilers were equipped with temperature, salinity and oxygen sensors.…”

Section: The Surveymentioning

confidence: 99%

“…6a) is lower than 8 • C over the western and central Black Sea reaching 10 • C around the eastern coast. This low SST enables cold intermediate water to form over large areas (for the water mass formation in the Black Sea see Ovchinnikov and Popov, 1987;Stanev et al, 2003). The lowest SST occurs in the northwestern shelf; this low-temperature area extends southward because of the transport along the western coasts.…”

Section: Upper Ocean Patternsmentioning

confidence: 99%

“…In the study of Konovalov et al (2003) these limits have been specified as 30 nmol L −1 for sulfide and 3 µmol L −1 for oxygen. As demonstrated by Stanev et al (2013), Argo floats' observations in the Black Sea equipped with an optode sensor can resolve these low oxygen concentrations. For a recent analysis of the spatial and temporal variability of chemical properties in the Black Sea based on historic data, see Tugrul et al (2014).…”

Section: Introductionmentioning

confidence: 99%

“…The reason to put the oxygen in the middle of our research focus is that we want to use in a coherent way high-resolution in time and space observations in parallel with numerical simulations. The recent observational activities using Argo floats equipped with oxygen sensors (Stanev et al, 2013) provided such data.…”

Section: Introductionmentioning

confidence: 99%

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Mixing in the Black Sea detected from the temporal and spatial variability of oxygen and sulfide – Argo float observations and numerical modelling

et al. 2014

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Abstract. The temporal and spatial variability of the upper ocean hydrochemistry in the Black Sea is analysed using data originating from profiling floats with oxygen sensors and carried out with a coupled three-dimensional circulationbiogeochemical model including 24 biochemical state variables. Major focus is on the dynamics of suboxic zone which is the interface separating oxygenated and anoxic waters. The scatter of oxygen data seen when plotted in density coordinates is larger than those for temperature, salinity and passive tracers. This scatter is indicative of vigorous biogeochemical reactions in the suboxic zone, which acts as a boundary layer or internal sink for oxygen. This internal sink affects the mixing patterns of oxygen compared to the ones of conservative tracers. Two different regimes of ventilation of pycnocline were clearly identified: a gyre-dominated (cyclonic) regime in winter and a coastal boundary layer (anticyclonic eddy)-dominated regime in summer. These contrasting states are characterized by very different pathways of oxygen intrusions along the isopycnals and vertical oxygen conveyor belt organized in multiple-layered cells formed in each gyre. The contribution of the three-dimensional modelling to the understanding of the Black Sea hydro-chemistry, and in particular the coast-to-open-sea mixing, is also demonstrated. Evidence is given that the formation of oxic waters and of cold intermediate waters, although triggered by the same physical process, each follow a different evolution. The difference in the depths of the temperature minimum and the oxygen maximum indicates that the variability of oxygen is not only just a response to physical forcing and changes in the surface conditions, but undergoes its own evolution.

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Section: The Surveymentioning

confidence: 99%

Section: Upper Ocean Patternsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mixing in the Black Sea detected from the temporal and spatial variability of oxygen and sulfide – Argo float observations and numerical modelling

et al. 2014

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“…0094-8276/05/2004GL021580 L03604 unlike the CIL, the sub-oxic layer remains isolated from direct surface forcing throughout the year. More recently, comprehensive analysis of satellite data, surveys and modeling indicates that formation is possible throughout the Black Sea with regional variations that vary from year-toyear [Stanev et al, 2003]. …”

Section: Introductionmentioning

confidence: 99%

Surface ventilation of the Black Sea's cold intermediate layer in the middle of the western gyre

Gregg

Yakushev

2005

Geophysical Research Letters

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[1] Understanding the origin of the shallow temperature minimum, known as the Cold Intermediate Layer (CIL), in the Black Sea has long been hampered by the scarcity of winter observations. During March 2003, we observed a cold-air outbreak over the center of the Black Sea's Western Gyre. Freezing winds drove convection that cooled the surface mixed layer to 6.1°C and deepened it to 40 m, directly ventilating the upper 80% of the CIL, whose lower boundary was at 49 m. Concentrations of dissolved oxygen were 350 mM in the mixed layer and decreased rapidly to 70 mM at the base of the CIL, 9 m below the mixed layer. A few meters deeper, at the top of the Sub-Oxic Layer (SOL), both oxygen and hydrogen sulfide became undetectable (<5 mM and <1 mM, respectively). Microstructure profiles revealed intermittent turbulence in the oxycline below the mixed layer. Average rates of turbulent dissipation were 10 À9 -10 À8 W kg À1 . The accompanying mixing produced diapycnal diffusivities, K r , that were only (1 -4) Â 10 À6 m 2 s À1 . Consequently, turbulent fluxes were too weak to renew significantly either the lower 20% of the CIL or the SOL, whose top was 4 m below the bottom of the CIL and hence well-removed from direct surface replenishment. Citation: Gregg, M. C., and E. Yakushev (2005), Surface ventilation of the Black Sea's cold intermediate layer in the middle of the western gyre, Geophys. Res. Lett., 32, L03604,

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Geochemistry of the Black Sea during the last 15 kyr: A protracted evolution of its hydrography and ecology

Piper

2016

Paleoceanography

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The Black Sea is a 2200 m deep anoxic, marine sea connected to the Mediterranean Sea via the Dardanelles Strait, Marmara Sea, and the 3 km wide, 35 m deep Bosphorus Strait. The biogeochemistry of sediment from the Anatolia slope has recorded changes to the hydrography leading up to and following the input of Mediterranean water at ~9.4 ka (103 years B.P.), when global sea level rose to the level of the Bosphorus sill and high‐salinity water from the Mediterranean began to spill into the then brackish lake. The water initially mixed little with the lake water but cascaded to the bottom where it remained essentially isolated for ~1.6 kyr, the time required to fill the basin from the bottom up at its present input rate. The accumulation of Mo in the seafloor sediments, a proxy of bottom‐water anoxia, increased sharply at ~8.6 ka, when bacterial respiration in the bottom water advanced to SO42− reduction by the oxidation of organic detritus that settled out of the photic zone. Its accumulation remained elevated to ~5.6 ka, when it decreased 60%, only to again increase slightly at ~2.0 ka. The accumulation of Corg, a proxy of primary productivity, increased threefold to fourfold at ~7.8 ka, when upward mixing of the high‐salinity bottom water replaced the then thin veneer of the brackish photic zone in less than 50 years. From that time onward, the accumulation of Corg, Mo, and additional trace metals has reflected the hydrography of the basin and Bosphorus Strait, controlled largely by climate.

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Control of Black Sea intermediate water mass formation by dynamics and topography: Comparison of numerical simulations, surveys and satellite data

Cited by 57 publications

References 0 publications

Mixing in the Black Sea detected from the temporal and spatial variability of oxygen and sulfide – Argo float observations and numerical modelling

Mixing in the Black Sea detected from the temporal and spatial variability of oxygen and sulfide – Argo float observations and numerical modelling

Surface ventilation of the Black Sea's cold intermediate layer in the middle of the western gyre

Geochemistry of the Black Sea during the last 15 kyr: A protracted evolution of its hydrography and ecology

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