The significance of wave–current interaction on modelled wave fields in the Baltic Sea

2020 ◽  
Author(s):  
Hedi Kanarik ◽  
Laura Tuomi ◽  
Jan-Victor Björkqvist ◽  
Tuomas Kärnä ◽  
Antti Westerlund
Keyword(s):  
Baltic Sea ◽  
Wave Spectrum ◽  
Hydrodynamical Model ◽  
Gulf Of Finland ◽  
Surface Currents ◽  
The Baltic Sea ◽  
Notable Effect ◽  
Baltic Proper ◽  
The Baltic ◽  
The Gulf Of Finland

<p>Currents in the Baltic Sea are relatively weak and are thus often expected to have a negligible effect on sea surface waves. To evaluate the magnitude of wave–current interactions in the Baltic Sea, we ran the third generation wave model WAM with and without surface currents from the 3D hydrodynamical model Nemo4. The results showed that the currents have a notable effect on wave field only on rare occasions and that the effects are largest in coastal areas of the Baltic Proper, most notably in the western Gotland Basin, and the Gulf of Finland. The simulations showed that the currents in the Baltic Sea can cause differences of significant wave height up to tens of centimeters. More notable effect was the change in the peak of the wave spectrum from swell to wind driven waves and vice versa in some occasions. In our study w<span>e mostly focus on the events of strong wave–current interactions in the northern Baltic Proper and Gulf of Finland as we have measured wave spectra available from these locations. From the comparison with wave buoy measurements we see that implementing surface currents</span> <span>slightly improves the </span><span>m</span><span>odelled peak period in the Gulf of Finland.</span> <span>The Gulf of Finland is of special interest also because a group of ADCP’s were installed close to the wave buoy. The current measurements from these devices can therefore be used to evaluate the accuracy of the currents in the hydrodynamical model. </span></p>

scholarly journals Improving Baltic Sea wave forecasts using modelled surface currents

2021 ◽  
Author(s):  
Hedi Kanarik ◽  
Laura Tuomi ◽  
Jan-Victor Björkqvist ◽  
Tuomas Kärnä
Keyword(s):  
Baltic Sea ◽  
Model Simulation ◽  
Coastal Areas ◽  
Gulf Of Finland ◽  
Surface Currents ◽  
The Baltic Sea ◽  
Peak Period ◽  
Wind Sea ◽  
The Baltic ◽  
The Gulf Of Finland

AbstractCurrents in the Baltic Sea are generally weak, but during strong winds they can grow high enough to affect the surface wave propagation and evolution. To evaluate the significance of wave-current interactions in the Baltic Sea, we conducted a study using the wave model WAM, comparing a run without surface currents to one with current forcing from a NEMO hydrodynamical model simulation. The overall changes to the wave field caused by currents were quite small. Changes of over 10 cm in significant wave height (SWH) or 1 s in the peak period (Tp) occurred only in some areas and typically less than 3% of the time. Current refraction changed the SWH annual mean by up to 2 cm, but changes up to 60 cm were seen in the maximum values. Tp had occasionally large changes due to shifts in the peak energy in two-peaked swell and wind-sea spectra. Including currents typically led to a stronger changes in swell energy compared to the changes in wind sea energy. A comparison with a wave buoy in the Gulf of Finland showed that this change in the swell energy improved the accuracy of the simulation in this narrow gulf. Current-induced refraction was most prominent near the coastal areas, where current speed occasionally exceeded 0.3 m/s. In general, SWH decreased in the coastal areas with strong currents and slightly increased in adjacent open sea areas. The current effects were most frequent in the Gulf of Finland, the Western Gotland Basin and the Åland Sea.

Physical drivers of oxygen depletion in the Central and Eastern Baltic Sea

2020 ◽  
Author(s):  
Taavi Liblik ◽  
Stella-Theresa Stoicescu ◽  
Jaan Laanemets ◽  
Oliver Samlas ◽  
Kai Salm ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Deep Layer ◽  
Oxygen Depletion ◽  
Estuarine Circulation ◽  
Gulf Of Finland ◽  
The Baltic Sea ◽  
Gulf Of Riga ◽  
Baltic Proper ◽  
The Baltic ◽  
The Gulf Of Finland

<p>Eutrophication and consequent increase in biomass production and sedimentation of organic material cause oxygen depletion of the deep layers and an increase in hypoxic bottom areas in the Baltic Sea.</p><p>The Baltic Sea – a semi-enclosed brackish sea – has restricted water exchange with the North Sea. High fresh water runoff and sporadic inflows of saline water through the Danish Straits maintain stratification. Seasonal thermocline and quasi-permanent halocline, their vertical location, shape and strength are sensitive to atmospheric forcing and influence the oxygen depletion in the near-bottom layer. Physical processes altering deoxygenation in the three sub-basins of the Baltic Sea (Baltic Proper, Gulf of Finland and Gulf of Riga) are under scope of the present overview. Permanent halocline is present in the deep Baltic Proper, while in the Gulf of Finland, it occasionally vanishes during winter. Complete mixing occurs in each winter in the shallow Gulf of Riga separated from the Baltic Proper by the sill. We show that the bathymetry, combined with physical drivers, causes distinct spatial and temporal patterns of oxygen depletion in the basins. The results presented here are a summary of in-situ measurement campaigns conducted by the research vessel, underwater glider, autonomous vertical profiler and bottom moorings in 2011–2020.</p><p>Large barotropic inflows from the North Sea temporarily ventilate the deep layer of the Central Baltic Proper, but rather intensify hypoxia in the Northern Baltic Proper and the Gulf of Finland. Wind-driven estuarine circulation alterations shape the hypoxic area and volume in the Gulf of Finland considerably. Seaward winds support estuarine circulation and the advection of hypoxic saltier water of the Northern Baltic Proper into the gulf deep layer. The landward wind can reverse estuarine circulation, the collapse of stratification and mixing of the whole water column in winter (when the seasonal thermocline is absent), thus, temporarily improving oxygen conditions in the deep layer of the gulf. Intrusion of cold saltier water of the Baltic Proper over the sill into the Gulf of Riga deep layer strengthens water column stratification and supports hypoxia formation in summer. Such a water exchange regime is related to the northerly wind forced upwelling along the eastern coast of the Baltic Proper. The role of submesoscale processes on vertical mixing and deep layer ventilation is still unclear, and the data of high-resolution in situ measurements in the Baltic Sea is limited yet. Preliminary results from the dedicated underwater glider surveys conducted at the coastal slope of Eastern Baltic Proper in 2019-2020 will be presented.</p>

scholarly journals An integrated simulation model to evaluate national measures for the abatement of agricultural nutrients in the Baltic Sea

2009 ◽  
Vol 18 (3-4) ◽  
pp. 440-459 ◽  
Author(s):  
K. HYYTIÄINEN ◽  
H. AHTIAINEN ◽  
J. HEIKKILÄ
Keyword(s):  
Water Quality ◽  
Simulation Model ◽  
Baltic Sea ◽  
Arable Land ◽  
Gulf Of Finland ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
The Baltic ◽  
Bothnian Bay ◽  
The Gulf Of Finland

This study introduces a prototype model for evaluating measures to abate agricultural nutrients in the Baltic Sea from a Finnish national perspective. The stochastic simulation model integrates nutrient dynamics of nitrogen and phosphorus in the sea basins adjoining the Finnish coast, nutrient loads from land and other sources, benefits from nutrient abatement (in the form of recreation and other ecosystem services) and the costs of agricultural abatement activities. The aim of the study is to present the overall structure of the model and to demonstrate its potential using preliminary parameters. The model is made flexible for further improvements in all of its ecological and economic components. The results of a sensitivity analysis suggest that investments in reducing the nutrient load from arable land in Finland would become profitable only if the neighboring countries in the northern Baltic committed themselves to similar reductions. Environmental investments for improving water quality yield the highest returns for the Bothnian Bay and the Gulf of Finland, with smaller returns for the Bothnian Sea. Somewhat surprisingly, in the Bothnian Bay the abatement activities become profitable from the national viewpoint, because the riverine loads from Finland represent a high proportion of the total nutrient loads. In the Gulf of Finland, this proportion is low, but the size of the coastal population benefiting from improved water quality is high.;

scholarly journals Influence of St. Petersburg urban rivers on the inflow of pollutants into the Baltic Sea

2020 ◽  
Vol 163 ◽  
pp. 03006
Author(s):  
Stepan Klubov ◽  
Victor Tretyakov
Keyword(s):  
Baltic Sea ◽  
Gulf Of Finland ◽  
Urban Rivers ◽  
The Baltic Sea ◽  
Saint Petersburg ◽  
The Baltic ◽  
The Gulf Of Finland

The results of the calculation of the inflow of pollutants into the Gulf of Finland with the outflow from Saint Petersburg watercourses are considered. Data of regular hydrochemical observations by State Unitary Enterprise “Vodokanal of Saint Petersburg” for 2018 were used for the calculation. The contribution of the megalopolis of Saint Petersburg to change of the pollutants inflow is estimated.

Assessment of biogenous load on the Gulf of Finland exerted from the Russian territory

2020 ◽  
Author(s):  
Nikolai Voronov ◽  
Nataly Victorova ◽  
Dmitry Shilov
Keyword(s):  
Baltic Sea ◽  
Point Sources ◽  
Gulf Of Finland ◽  
Observation Data ◽  
The Baltic Sea ◽  
Russian Territory ◽  
Catchment Areas ◽  
The Baltic ◽  
Bodies Of Water ◽  
The Gulf Of Finland

<p>The purpose of the essay was analysis and evaluation of the load generated by pollutants in the Russian part of the catchment area directly entering the Baltic Sea, as well as consideration of pro-rata contribution of all sources in the formation of factual biogenous load at the catchment areas of rivers flowing into the Gulf of Finland.</p><p>The assessment of biogenous load was made on the basis of observation data, statistical reporting data, mathematical modelling data and additional monitoring data for bodies of water in previously uncontrolled areas. To assess the amount of biogenous input from uncontrolled tributaries of the Gulf of Finland, field observations of the discharge and concentration of pollutants over a number of past years were analyzed and generalized.</p><p>It is noted that there has been a tendency towards reduction of pollutants for a number of substances in the last decade, as shown by the analysis. It is demonstrated that a significant decrease is due to reduced load from point sources that discharge pollutants directly to the Baltic Sea and its bays. Some proposals are presented for improving the Russian system of monitoring the load exerted on water bodies.</p>

High-resolution dynamics of the spring bloom in the Gulf of Finland of the Baltic Sea

2014 ◽  
Vol 129 ◽  
pp. 135-149 ◽  
Author(s):  
Inga Lips ◽  
Nelli Rünk ◽  
Villu Kikas ◽  
Aet Meerits ◽  
Urmas Lips
Keyword(s):  
High Resolution ◽  
Baltic Sea ◽  
Spring Bloom ◽  
Gulf Of Finland ◽  
The Baltic Sea ◽  
The Baltic ◽  
The Gulf Of Finland

scholarly journals Foreign Ships in Vulnerable Waters: Coastal Jurisdiction over Vessel-Source Pollution with Special Reference to the Baltic Sea

2005 ◽  
Vol 33 (2) ◽  
pp. 256-266 ◽  
Author(s):  
Kari Hakapää
Keyword(s):  
Baltic Sea ◽  
Special Reference ◽  
Marine Environment ◽  
Climatic Conditions ◽  
Gulf Of Finland ◽  
Topical Issue ◽  
The Baltic Sea ◽  
The Baltic ◽  
Sea Area ◽  
The Gulf Of Finland

Protection and preservation of the marine environment is a topical issue around the Baltic Sea. Not least does it refer to vessel-source pollution. The Baltic Sea is a particularly vulnerable sea area with its narrow waters, often severe climatic conditions, and growing tanker traffic, especially to and from Russian ports at the far end of the Gulf of Finland. By way of example, oil transports in the Gulf of Finland tripled in 1995 to 2003, recently reaching to some 78 million tons a year.

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