Structure of unsteady overflow in the Słupsk Furrow of the Baltic Sea

Zhurbas, Victor; Elken, Jüri; Пака, В. Т.; Piechura, Jan; Väli, Germo; Chubarenko, Irina; Golenko, N. N.; Щука, С. А.

doi:10.1029/2011jc007284

Cited by 20 publications

(6 citation statements)

References 47 publications

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“…When the NW wind has grown to severe gale, the low-salinity water in the upper layer rushed to the southwest owing to the Ekman transport, causing an intensification of the oppositely directed northeast flow of the saltwater in the lower layer through the Hoburg Channel. The situation is quite similar to that of the Słupsk Furrow, where the northerly and easterly winds drive the westward transport in the upper layer and intensify the eastward transport of the saltwater in the lower layer of the Furrow, while the westerly and southerly winds result in weakening and even blocking the eastward transport of the saltwater through the Furrow (Krauss and Brügge, 1991;Zhurbas et al, 2012).…”

Section: Near-bottom Currentssupporting

confidence: 53%

Innovative Closely Spaced Profiling and Current Velocity Measurements in the Southern Baltic Sea in 2016–2018 With Special Reference to the Bottom Layer

et al. 2019

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A solution to the problem of determination of spatial variability of oceanographic fields, which contained a fine structure resolution higher than what was possible previously using towed scanning probes, was presented for the Baltic Sea. Another concurrently solved problem consisted in obtaining data on the structure of waters in the bottom layer, which was difficult to implement by way of application of previous methods. Instead of scanning along inclined paths, a new measurement technique allows for a quasi-free probe drop with a constant sink rate and which reaches the bottom at each dive cycle along the route of the ship, independent of the pitch of the ship and optimal for the applied probe. The new measurement technique is simpler and more efficient than the previous one. In addition, the problem of measuring the velocity of both very weak and strong currents in a thin bottom layer, including stagnant zones, slopes, sills, and underwater channels, was suggested to be solved using clusters consisting of a sufficiently large number of autonomous Tilt Current Meters (TCM) of original design. The innovation benefits are illustrated by the results of a monitoring campaign that was carried out in the southern Baltic Sea in 2016-2018. Among the new findings is the highest ever recorded temperature, 14.3 • C, in the halocline of the Bornholm Basin, measured after a baroclinic inflow event in early Autumn 2018, and an extraordinarily large current velocity of saltwater flow of more than 0.5 m/s, recorded by a TCM within a 1 m thick bottom layer at the eastern slope of the Hoburg Channel during a period when the northwesterly wind had intensified to a severe gale.

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Section: Near-bottom Currentssupporting

confidence: 53%

Innovative Closely Spaced Profiling and Current Velocity Measurements in the Southern Baltic Sea in 2016–2018 With Special Reference to the Bottom Layer

et al. 2019

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“…The mean northward component of the current was 10 cm s -1 , which can be explained by the mean density structure (Fig. 15a) and is typical for the gravity current in a channel (Zhurbas et al, 2012). This current is an important deeper limb of the Baltic haline conveyor belt (Döös et al, 2004).…”

Section: Discussionmentioning

confidence: 80%

Quasi-steady circulation regimes in the Baltic Sea

Liblik

Väli

Salm

et al. 2022

Preprint

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Abstract. Circulation plays an essential role in the creation of physical and biogeochemical fluxes in the Baltic Sea. The main aim of the work was to study the quasi-steady circulation patterns under prevailing forcing conditions. Six months of continuous vertical profiling and fixed-point measurements of currents, two monthly underwater glider surveys, and numerical modelling were applied in the central Baltic Sea. The vertical structure of currents was strongly linked to the location of the two pycnoclines: the seasonal thermocline and the halocline. The vertical movements of pycnoclines and velocity shear maxima were synchronous. The quasi-steady circulation patterns were in geostrophic balance and high-persistent. The persistent patterns included circulation features such as upwelling, downwelling, boundary current, and sub-halocline gravity current. The patterns had a prevailing zonal scale of 5–60 km and considerably higher magnitude and different direction than the long-term mean circulation pattern. Northward (southward) geostrophic boundary current in the upper layer was observed along the eastern coast of the central Baltic in the case of southwesterly (northerly) wind. The geostrophic current at the boundary was often a consequence of wind-driven, across-shore advection. The sub-halocline quasi-permanent gravity current with a width of 10–30 km from the Gotland Deep to the north over the narrow sill separating the Farö Deep and Northern Deep was detected in the simulation, and it was confirmed by an Argo float trajectory. According to the simulation, a strong flow, mostly to the north, with a zonal scale of 5 km occurred at the sill. This current is an important deeper limb of the overturning circulation of the Baltic Sea. The current is stronger with northerly winds and restricted by the southwesterly winds. The circulation regime has an annual cycle due to seasonality in the forcing. Boundary currents are stronger and more frequently northward during the winter period. The sub-halocline current towards the north is strongest in March–May and weakest in November–December.

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“…A detailed description of the method for geostrophic estimates of the AW volume flow rate is presented in the paper (Zhurbas N., 2019). (Arneborg et al, 2007;Zhurbas et al, 2012), so it is natural that the water flowing through St. Anna Trough in the Eurasian basin is transported by a gravity current. It is obvious that in case of near-bottom gravity current the no motion depth level for geostrophic calculations is implied to be well above the current.…”

Section: Throughmentioning

confidence: 99%

Assessment of variability of the thermohaline structure and transport of Atlantic water in the Arctic Ocean based on NABOS CTD data

Zhurbas

Kuzmina

2019

Preprint

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Abstract. Data of CTD transects across continental slope of the Eurasian Basin and the St. Anna Trough performed during NABOS (Nansen and Amundsen Basins Observing System) project in 2003–2015 are used to assess transport and propagation features of the Atlantic Water (AW) in the Arctic Ocean. Estimates of θ-S indices and volume flow rate of the current carrying the AW in the Eurasian Basin were obtained. The assessments were based on the analysis of CTD data including 33 sections in the Eurasian Basin, 4 transects in the St. Anna Trough and 2 transects in the Makarov Basin; additionally a CTD transect of the PolarStern-1996 expedition (PS-96) was considered. Using spatial distributions of temperature, salinity, and density on the transects and applying θ-S analysis, the variability of thermohaline pattern on the AW pathway along the slope of Eurasian Basin was investigated. The Fram Strait branch of the Atlantic Water (FSBW) was satisfactorily identified on all transects, including two transects in the Makarov Basin (along 159° E), while the сold waters, which can be associated with the influence of the Barents Sea branch of the Atlantic water (BSBW), on the transects along 126° E, 142° E and 159° E, were observed in the depth range below 800 m and had a negligible effect on the spatial structure of isopycnic surfaces. Special attention was paid to the variability of the volume flow rate of the AW propagating along the continental slope of the Eurasian Basin. The geostrophic volume flow rate was calculated using the dynamic method. An interpretation of the spatial and temporal variability of hydrological parameters characterizing the flow of the AW in the Eurasian Basin is presented. The geostrophic volume flow rate decreases significantly farther away from the areas of the AW inflow to the Eurasian Basin. Thus, the geostrophic estimate of the volume rate for the AW flow in the Makarov Basin at 159° E was found to be more than an order of magnitude smaller than the estimates of the volume flow rate in the Eurasian Basin, implying that the major part of the AW entering the Arctic Ocean circulates cyclonically within the Nansen and Amundsen Basins. There is an absolute maximum of θmax (AW core temperature) in 2006–2008 time series and a maximum in 2013, but only at 103° E. Salinity S(θmax) (AW core salinity) time series display an increase of the AW salinity in 2006–2008 and 2013 (at 103° E) that can be referred to as a AW salinization in the early 2000-ies. The maxima of θmax and S(θmax) in 2006–2008 and 2013 were accompanied by the volume flow rate highs. Additionally the time average volume rates were calculated for the FSBW flow (in the longitude range 31–92° E), for the BSBW flow in the St. Anna Trough and for a combined FSBW and BSBW flow in longitude range 94–107° E. A detailed discussion of the results is presented.

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Structure of unsteady overflow in the Słupsk Furrow of the Baltic Sea

Cited by 20 publications

References 47 publications

Innovative Closely Spaced Profiling and Current Velocity Measurements in the Southern Baltic Sea in 2016–2018 With Special Reference to the Bottom Layer

Innovative Closely Spaced Profiling and Current Velocity Measurements in the Southern Baltic Sea in 2016–2018 With Special Reference to the Bottom Layer

Quasi-steady circulation regimes in the Baltic Sea

Assessment of variability of the thermohaline structure and transport of Atlantic water in the Arctic Ocean based on NABOS CTD data

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