PRESENT VARIATIONS OF THE BALTIC SEA LEVEL AND WATER BALANCE

2018 ◽  
Author(s):  
С. Гордеева ◽  
S. Gordeeva ◽  
В. Малинин ◽  
V. Malinin ◽  
М. Дрозд ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
World Ocean ◽  
The Baltic Sea ◽  
Steric Sea Level ◽  
Sea Level Fluctuations ◽  
North East ◽  
The North ◽  
Ocean Level ◽  
The Baltic

The Baltic Sea level fluctuations have significant trends. The sea level rises in all Baltic coastsb with at different rates. Sweden coast "breathes" as well as the World Ocean level. Sea level rising on the south and the north-east coast of the Baltic Sea is lower. The trend component is not determined by interannual variations of steric sea level, the vertical water exchange and baltic river runoff. Consequently, the secular trends in sea level are caused by long-term changes in the resulting flow of water through the Danish straits. This is confirmed by changes in salinity of the Baltic Sea.

scholarly journals Contribution of atmospheric circulation to recent off-shore sea-level variations in the Baltic Sea and the North Sea

2018 ◽  
Vol 9 (1) ◽  
pp. 69-90 ◽  
Author(s):  
Sitar Karabil ◽  
Eduardo Zorita ◽  
Birgit Hünicke
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
North Sea ◽  
Circulation Pattern ◽  
Net Energy ◽  
The Baltic Sea ◽  
Sea Level Variability ◽  
The North ◽  
The North Sea ◽  
The Baltic

Abstract. The main purpose of this study is to quantify the contribution of atmospheric factors to recent off-shore sea-level variability in the Baltic Sea and the North Sea on interannual timescales. For this purpose, we statistically analysed sea-level records from tide gauges and satellite altimetry and several climatic data sets covering the last century. Previous studies had concluded that the North Atlantic Oscillation (NAO) is the main pattern of atmospheric variability affecting sea level in the Baltic Sea and the North Sea in wintertime. However, we identify a different atmospheric circulation pattern that is more closely connected to sea-level variability than the NAO. This circulation pattern displays a link to sea level that remains stable through the 20th century, in contrast to the much more variable link between sea level and the NAO. We denote this atmospheric variability mode as the Baltic Sea and North Sea Oscillation (BANOS) index. The sea-level pressure (SLP) BANOS pattern displays an SLP dipole with centres of action located over (5° W, 45° N) and (20° E, 70° N) and this is distinct from the standard NAO SLP pattern in wintertime. In summertime, the discrepancy between the SLP BANOS and NAO patterns becomes clearer, with centres of action of the former located over (30° E, 45° N) and (20° E, 60° N). This index has a stronger connection to off-shore sea-level variability in the study area than the NAO in wintertime for the period 1993–2013, explaining locally up to 90 % of the interannual sea-level variance in winter and up to 79 % in summer. The eastern part of the Gulf of Finland is the area where the BANOS index is most sensitive to sea level in wintertime, whereas the Gulf of Riga is the most sensitive region in summertime. In the North Sea region, the maximum sea-level sensitivity to the BANOS pattern is located in the German Bight for both winter and summer seasons. We investigated, and when possible quantified, the contribution of several physical mechanisms which may explain the link between the sea-level variability and the atmospheric pattern described by the BANOS index. These mechanisms include the inverse barometer effect (IBE), freshwater balance, net energy surface flux and wind-induced water transport. We found that the most important mechanism is the IBE in both wintertime and summertime. Assuming a complete equilibration of seasonal sea level to the SLP gradients over this region, the IBE can explain up to 88 % of the sea-level variability attributed to the BANOS index in wintertime and 34 % in summertime. The net energy flux at the surface is found to be an important factor for the variation of sea level, explaining 35 % of sea-level variance in wintertime and a very small amount in summer. The freshwater flux could only explain 27 % of the variability in summertime and a negligible part in winter. In contrast to the NAO, the direct wind forcing associated with the SLP BANOS pattern does not lead to transport of water from the North Sea into the Baltic Sea in wintertime.

scholarly journals Nemo-Nordic 2.0: Operational marine forecast model for the Baltic Sea

2021 ◽  
Author(s):  
Tuomas Kärnä ◽  
Patrik Ljungemyr ◽  
Saeed Falahat ◽  
Ida Ringgaard ◽  
Lars Axell ◽  
...  
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
Sea Level ◽  
Ocean Circulation ◽  
Circulation Model ◽  
Forecast Model ◽  
The Baltic Sea ◽  
Baltic Basin ◽  
The North ◽  
The Baltic

Abstract. This paper describes Nemo-Nordic 2.0, an operational marine forecast model for the Baltic Sea. The model is based on the NEMO (Nucleus for European Modelling of the Ocean) circulation model and the previous Nemo-Nordic 1.0 configuration by Hordoir et al. [Geosci. Model Dev., 12, 363–386, 2019]. The most notable updates include the switch from NEMO version 3.6 to 4.0, updated model bathymetry and revised bottom friction formulation. The model domain covers the Baltic and the North Seas with approximately 1 nautical mile resolution. Vertical grid resolution has been increased from 3 to 1 m in the surface layer. In addition, the numerical solver configuration has been revised to reduce artificial mixing to improve the representation of inflow events. Sea-ice is modeled with the SI3 model instead of LIM3. The model is validated against sea level, water temperature and salinity observations, as well as Baltic Sea ice chart data for a two-year hindcast simulation. Sea level root mean square deviation (RMSD) is typically within 10 cm throughout the Baltic basin. Seasonal sea surface temperature variation is well captured, although the model exhibits a negative bias of approximately −0.5 °C. Salinity RMSD is typically below 1.5 g/kg. The model captures the 2014 Major Baltic Inflow event and its propagation to the Gotland Deep. The skill analysis demonstrates that Nemo-Nordic 2.0 can reproduce the hydrographic features of the Baltic Sea.

A molecular phylogeny of the north-east Atlantic species of the genusIdotea(Isopoda) with focus on the Baltic Sea

2016 ◽  
Vol 46 (2) ◽  
pp. 188-199 ◽  
Author(s):  
Marina Panova ◽  
Arne Nygren ◽  
Per R. Jonsson ◽  
Sonja Leidenberger
Keyword(s):  
Molecular Phylogeny ◽  
Baltic Sea ◽  
East Atlantic ◽  
The Baltic Sea ◽  
North East ◽  
The North ◽  
The Baltic

scholarly journals Absolute Baltic Sea Level Trends in the Satellite Altimetry Era: A  Revisit

2021 ◽  
Author(s):  
Julius Oelsmann ◽  
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
Satellite Altimetry ◽  
Altimetry Data ◽  
The South ◽  
The Baltic Sea ◽  
The North ◽  
Sea Level Anomalies ◽  
South West ◽  
The Baltic

<p>For sea level studies, coastal adaptation, and planning for future sea level scenarios, regional responses require regionally-tailored sea level information. Global sea level products from satellite altimeter missions are now available through the European Space Agency’s (ESA) Climate Change Initiative Sea Level Project (SL_cci). However, these global datasets are not entirely appropriate for supporting regional actions. Particularly for the Baltic Sea region, complications such as coastal complexity and sea-ice restrain our ability to exploit radar altimetry data.</p><p>This presentation highlights the benefits and opportunities offered by such regionalised advances, through an examination by the ESA-funded Baltic SEAL project (http://balticseal.eu/). We present the challenges faced, and solutions implemented, to develop new dedicated along-track and gridded sea level datasets for Baltic Sea stakeholders, spanning the years 1995-2019. Advances in waveform classification and altimetry echo-fitting, expansion of echo-fitting to a wide range of altimetry missions (including Delay-Doppler altimeters), and Baltic-focused multi-mission cross calibration, enable all altimetry missions’ data to be integrated into a final gridded product.</p><p>This gridded product, and a range of altimetry datasets, offer new insights into the Baltic Sea’s mean sea level and its variability during 1995-2019. Here, we focus on the analysis of sea level trends in the region using both tide gauge and altimetry data. The Baltic SEAL absolute sea level trend at the coast better aligns with information from the in-situ stations, when compared to current global products. The rise in sea level is statistically significant in the region of study and higher in winter than in summer. A gradient of over 3 mm/yr in sea level rise is observed, with sea levels in the north and east of the basin rising more than in the south-west. Part of this gradient (about 1 mm/yr) is directly explained by a regression analysis of the wind contribution on the sea level time series. A sub-basin analysis comparing the northernmost part (Bay of Bothnia) with the south-west reveals that the differences in winter sea level anomalies are related to different phases of the North-Atlantic Oscillation (0.71 correlation coefficient). Sea level anomalies are higher in the Bay of Bothnia when winter wind forcing pushes waters through Ekman transport from the south-west towards east and north.</p><p>The study also demonstrates the maturity of enhanced satellite altimetry products to support local sea level studies in areas characterised by complex coastlines or sea-ice coverage. The processing chain used in this study can be exported to other regions, in particular to test the applicability in regions affected by larger ocean tides. We promote further exploitation and identification of further synergies with other efforts focused on relevant oceanic variables for societal applications.</p>

Baltic Sea Level: Past, Present, and Future

2019 ◽  
Author(s):  
Ralf Weisse ◽  
Birgit Hünicke
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
Water Surface ◽  
Wind Waves ◽  
World Ocean ◽  
The Baltic Sea ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Mean Sea Level ◽  
The Baltic

A multitude of geophysical processes contribute to and determine variations and changes in the height of the Baltic Sea water surface. These processes act on a broad range of characteristic spatial and timescales ranging from a few seconds to millennia. On very long timescales, the northern parts of the Baltic are uplifting due to the still ongoing visco-elastic response of the Earth to the last deglaciation, and mean sea level is decreasing in these regions. Over centuries, the Baltic Sea responds to changes in global and North Atlantic mean sea level. Processes affecting global mean sea level, such as warming of the world ocean or melting of glaciers and of polar ice sheets, do have an imprint on Baltic Sea levels. Over decades, variations and changes in atmospheric circulation affect transport through the Danish Straits connecting the Baltic and North seas. As a result, the amount of water in the Baltic Sea and the height of the sea level vary. Similarly, atmospheric variability on shorter timescales down to a few days cause shorter period variations of transport through the Danish Straits and Baltic Sea level. On even shorter timescales, the Danish Straits act as a low pass filter, and high frequency variations of the water surface within the Baltic Sea such as storm surges, wind waves, or seiches are solely caused internally. All such processes have undergone considerable variations and changes in the past. Similarly, they are expected to show variations and changes in the future and across a broad range of scales, leaving their imprint on observed and potential future Baltic Sea level and its variability.

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