Refined estimates of water transport through the Åland Sea, Baltic Sea

Abstract. Water exchange through the Åland Sea, Baltic Sea, greatly affects the environmental conditions in the neighbouring Gulf of Bothnia. Recently observed changes in the eutrophication status of the Gulf of Bothnia may be connected to changing nutrient fluxes through the Åland Sea. Pathways and variability of sub-halocline northward-bound flows towards the Bothnian Sea are important for these studies. While the general nature of the water exchange is known, that knowledge is based on only a few studies that are somewhat limited in details. Notably, no high-resolution modelling studies of water exchange in the Åland Sea area have been published. In this study, we present a configuration of the NEMO 3D hydrodynamic model for the Åland Sea-Archipelago Sea area at around 500 m horizontal resolution. We then use it to study the water exchange in the Åland Sea. We first ran the model for the years 2013–2017 and validated the results, with a focus on the simulated current fields. We found that the model reproduced current direction distributions and layered structure of currents in the water column with reasonably good accuracy. Next, we used the model to calculate volume transports across several transects in the Åland Sea. These calculations provided new detail of water transport in the area. Time series of monthly mean volume transports showed a consistent northward transport in the deep layer. In the surface layer there was more variability: while net transport was towards the south, in several years some months in late summer or early autumn showed net transport to the north. Furthermore, based on our model calculations, it seems that dynamics in the Lågskär Deep are more complex than has been previously understood. While Lågskär Deep is the primary route of deep water exchange, still a significant volume of deep water enters the Åland Sea through the depression west of the Lågskär Deep. Better spatial and temporal coverage of current measurements is needed to further refine the understanding of water exchange in the area.

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Bathymetric Properties of the Baltic Sea

10.5194/os-2019-18 ◽

2019 ◽

Cited By ~ 1

Author(s):

Martin Jakobsson ◽

Christian Stranne ◽

Matt O'Regan ◽

Sarah L. Greenwood ◽

Bo Gustafsson ◽

...

Keyword(s):

High Resolution ◽

Baltic Sea ◽

Ocean Circulation ◽

Deep Water ◽

Water Exchange ◽

The Baltic Sea ◽

Resolution Mapping ◽

Baltic Proper ◽

Southern Side ◽

The Baltic

Abstract. Marine science and engineering commonly require reliable information about seafloor depth (bathymetry), e.g. for studies of ocean circulation, bottom habitats, fishing resources, sediment transport, geohazards and site selection for platforms and cables. Baltic Sea bathymetric properties are analysed here using the using the newly released Digital Bathymetric Model (DBM) by the European Marine Observation and Data Network (EMODnet). The analyses include hypsometry, volume, descriptive depth statistics, and km-scale seafloor ruggedness, i.e. terrain heterogeneity, for the Baltic Sea as a whole as well as for 17 sub-basins defined by the Baltic Marine Environment Protection Commission (HELCOM). We compare the new EMODnet DBM with IOWTOPO, the previously most widely used DBM of the Baltic Sea which has served as the primary gridded bathymetric resource in physical and environmental studies for nearly two decades. The area of deep water exchange between the Bothnian Sea and the Northern Baltic Proper across the Åland Sea is specifically analysed in terms of depths and locations of critical bathymetric sills. The EMODnet DBM provides a bathymetric sill depth of 88 m at the northern side of the Åland Sea and 60 m at the southern side, differing from previously identified sill depths of 100 and 70 m respectively. High-resolution multibeam bathymetry acquired from this deep water exchange path, where vigorous bottom currents interacted with the seafloor, allows us to assess what we are missing in presently available DBMs in terms of physical characterisation and our ability to then interpret seafloor processes and highlights the need for continued work towards complete high-resolution mapping of the Baltic Sea seafloor.

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Bathymetric properties of the Baltic Sea

Ocean Science ◽

10.5194/os-15-905-2019 ◽

2019 ◽

Vol 15 (4) ◽

pp. 905-924 ◽

Cited By ~ 2

Author(s):

Martin Jakobsson ◽

Christian Stranne ◽

Matt O'Regan ◽

Sarah L. Greenwood ◽

Bo Gustafsson ◽

...

Keyword(s):

High Resolution ◽

Baltic Sea ◽

Deep Water ◽

Water Exchange ◽

The Baltic Sea ◽

Resolution Mapping ◽

Baltic Proper ◽

Southern Side ◽

Northern Side ◽

The Baltic

Abstract. Baltic Sea bathymetric properties are analysed here using the newly released digital bathymetric model (DBM) by the European Marine Observation and Data Network (EMODnet). The analyses include hypsometry, volume, descriptive depth statistics, and kilometre-scale seafloor ruggedness, i.e. terrain heterogeneity, for the Baltic Sea as a whole as well as for 17 sub-basins defined by the Baltic Marine Environment Protection Commission (HELCOM). We compare the new EMODnet DBM with IOWTOPO the previously most widely used DBM of the Baltic Se aproduced by the Leibniz-Institut für Ostseeforschung Warnemünde (IOW), which has served as the primary gridded bathymetric resource in physical and environmental studies for nearly two decades. The area of deep water exchange between the Bothnian Sea and the Northern Baltic Proper across the Åland Sea is specifically analysed in terms of depths and locations of critical bathymetric sills. The EMODnet DBM provides a bathymetric sill depth of 88 m at the northern side of the Åland Sea and 60 m at the southern side, differing from previously identified sill depths of 100 and 70 m, respectively. High-resolution multibeam bathymetry acquired from this deep water exchange path, where vigorous bottom currents interacted with the seafloor, allows us to assess what presently available DBMs are missing in terms of physical characterization of the seafloor. Our study highlights the need for continued work towards complete high-resolution mapping of the Baltic Sea seafloor.

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Water Exchange and Water Transport in the Baltic Sea

Eutrophication in the Baltic Sea - Environmental Science and Engineering ◽

10.1007/978-3-540-70909-1_3 ◽

2008 ◽

pp. 69-89

Author(s):

Lars Håkanson ◽

Andreas C. Bryhn

Keyword(s):

Baltic Sea ◽

Water Transport ◽

Water Exchange ◽

The Baltic Sea ◽

The Baltic

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New look at the water exchange between the Arctic and North Atlantic in Iceland basin

Доклады Академии наук ◽

10.31857/s0869-56524854502-506 ◽

2019 ◽

Vol 485 (4) ◽

pp. 502-506

Author(s):

S. V. Gladyshev ◽

V. S. Gladyshev ◽

A. A. Klyuvitkin ◽

S. K. Gulev

Keyword(s):

Water Transport ◽

North Atlantic ◽

Deep Water ◽

Water Exchange ◽

The Arctic ◽

Eastern Slope ◽

Arctic Water ◽

Reykjanes Ridge ◽

Iceland Basin ◽

New Look

Based on the multi-year current observations along 59.5 N in the Subpolar North Atlantic multi-jet transport of arctic water along Reykjanes Ridge eastern slope producing Iceland-Scotland overflow water (ISOW) in Iceland Basin is revealed. Main jet properties as well as their contribution to the deep water transport are discussed.

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Modelling the water exchange of a fjord system on the Swedish west coast

10.5194/egusphere-egu21-892 ◽

2021 ◽

Author(s):

Sandra-Esther Brunnabend ◽

Lars Axell ◽

Maximo Garcia-Jove ◽

Lars Arneborg

Keyword(s):

West Coast ◽

Water Exchange ◽

Horizontal Resolution ◽

Swedish West Coast ◽

Fjord System ◽

The North ◽

The North Sea ◽

Model Setup ◽

Sea Area

<p>The water exchange between the Orust-Tj&#246;rn fjord system (located on the Swedish west coast) and the Skagerrak depends on different factors such as winds, tides, the water mass properties and circulation in the Skagerrak, as well as the density gradients between the southern and northern openings of the fjord system. These processes are not yet well understood as observations in the area are spatially and temporally sparse and the existing regional ocean models for the North Sea and Baltic Sea area have a too coarse resolution to sufficiently resolve the complex structures of the fjord system, such as the narrow and shallow channels that connect the different fjords in the system.</p><p>Therefore, we model the water exchange between the Orust-Tj&#246;rn fjord system and the Skagerrak using a NEMO3.6 model setup that has a horizontal resolution of 50 m. As validation, modelled temperature, salinity, velocity and sea surface height are compared with in-situ measurements. A detailed analysis of the modelled water flows in and out of the fjord system as well as between the different fjords will be presented. In addition, the different drivers of the modelled water exchange and their influence on the water properties above and below the sill depths in the fjords are investigated.</p>

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Numerical simulation of the impact of an integrated renovation project on the Maowei Sea hydrodynamic environment

Scientific Reports ◽

10.1038/s41598-021-96441-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Cui Wang ◽

Ling Cai ◽

Yaojian Wu ◽

Yurong Ouyang

Keyword(s):

Water Exchange ◽

Land Reclamation ◽

Three Dimensional ◽

Exchange Capacity ◽

Reclamation Project ◽

Hydrodynamic Environment ◽

Sea Area ◽

Water Quality Models ◽

The Impact ◽

Main Factor

AbstractIntegrated renovation projects are important for marine ecological environment protection. Three-dimensional hydrodynamics and water quality models are developed for the Maowei Sea to assess the hydrodynamic environment base on the MIKE3 software with high resolution meshes. The results showed that the flow velocity changed minimally after the project, decreasing by approximately 0.12 m/s in the east of the Maowei Sea area and increasing by approximately 0.01 m/s in the northeast of the Shajing Port. The decrease in tidal prism (~ 2.66 × 106 m3) was attributed to land reclamation, and accounted for just 0.86% of the pre-project level. The water exchange half-life increased by approximately 1 day, implying a slightly reduced water exchange capacity. Siltation occurred mainly in the reclamation and dredging areas, amounting to back-silting of approximately 2 cm/year. Reclamation project is the main factor causing the decrease of tidal volume and weakening the hydrodynamics in Maowei Sea. Adaptive management is necessary for such a comprehensive regulation project. According to the result, we suggest that reclamation works should strictly prohibit and dredging schemes should optimize in the subsequent regulation works.

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