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- Meier, H. E. M., et al.
(author)
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Ventilation of the Baltic Sea deep water: A brief review of present knowledge from observations and models
- 2006
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In: Oceanologia. - 0078-3234. ; 48, s. 133-164
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Journal article (peer-reviewed)abstract
- The ventilation of the Baltic Sea deep water is driven by either gale-forced barotropic or baroclinic salt water inflows. During the past two decades, the frequency of large barotropic inflows (mainly in winter) has decreased and the frequency of medium-intensity baroclinic inflows (observed in summer) has increased. As a result of entrainment of ambient oxygen-rich water, summer inflows are also important for the deep water ventilation. Recent process studies of salt water plumes suggest that the entrainment rates are generally smaller than those predicted by earlier entrainment models. In addition to the entrance area, the Slupsk Sill and the Slupsk Furrow are important locations for the transformation of water masses. Passing the Slupsk Furrow, both gravity-driven dense bottom flows and sub-surface cyclonic eddies, which are eroded laterally by thermohaline intrusions, ventilate the deep water of the eastern Gotland Basin. A recent study of the energy transfer from barotropic to baroclinic wave motion using a two-dimensional shallow water model suggests that about 30% of the energy needed below the halocline for deep water mixing is explained by the breaking of internal waves. In the deep water decade-long stagnation periods with decreasing oxygen and increasing hydrogen sulphide concentrations might be caused by anomalously large freshwater inflows and anomalously high mean zonal wind speeds. In different studies the typical response time scale of average salinity was estimated to be between approximately 20 and 30 years. The review summarizes recent research results and ends with a list of open questions and recommendations.
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| 2. |
- Burchard, H., et al.
(author)
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Dynamics of medium-intensity dense water plumes in the Arkona Basin, Western Baltic Sea
- 2005
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In: Ocean Dynamics. - : Springer Science and Business Media LLC. - 1616-7341 .- 1616-7228. ; 55:5-6, s. 391-402
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Journal article (peer-reviewed)abstract
- In this study, the dynamics of medium-intensity inflow events over Drogden Sill into the Arkona Sea are investigated. Idealised model simulations carried out with the General Estuarine Transport Model suggest that most of the salt transport during such inflow events occur north of Kriegers Flak, a shoal with less than 20 in water depth Surrounded by water depths of more than 40 in. This assumption about the pathway is supported by recent ship-based observations in the Arkona Sea during a medium-intensity inflow event. The propagation of a saline bottom plume could be observed during several days after having passed Drogden Sill. In the area north of Kriegers Flak the plume was about 10 m thick, and propagated with more than 0.5 m s(-1) and a salinity of tip to 20 psu (with ambient water salinity being 8 psu) eastwards. Although the model simulations were idealised, the Structural agreement between the observation and model result was good, The structure and pathways of these medium-intensity inflow events are of specific interest due to the plans for erecting extensive offshore wind farms in the Arkona Sea which may under certain circumstances lead to increased entrainment of ambient water into the bottom Plumes.
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