scholarly journals Spatiotemporal structure of Baltic free sea level oscillations in barotropic and baroclinic conditions from hydrodynamic modelling

Ocean Science ◽  
2021 ◽  
Vol 17 (2) ◽  
pp. 543-559
Author(s):  
Eugeny A. Zakharchuk ◽  
Natalia Tikhonova ◽  
Elena Zakharova ◽  
Alexei V. Kouraev
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
Low Frequency ◽  
The Baltic Sea ◽  
Meteorological Forcing ◽  
Maximum Variance ◽  
Sea Level Oscillations ◽  
The Baltic ◽  
Baroclinic Modes ◽  
Topographic Rossby Waves

Abstract. Free sea level oscillations in barotropic and baroclinic conditions were examined using numerical experiments based on a 3-D hydrodynamic model of the Baltic Sea. In a barotropic environment, the highest amplitudes of free sea level oscillations are observed in the northern Gulf of Bothnia, eastern Gulf of Finland, and south-western Baltic Sea. In these areas, the maximum variance appears within the frequency range corresponding to periods of 13–44 h. In a stratified environment, after the cessation of meteorological forcing, water masses relax to the equilibrium state in the form of mesoscale oscillations at the same frequencies as well as in the form of rapidly decaying low-frequency (seasonal) oscillations. The total amplitudes of free baroclinic perturbations are significantly larger than those of barotropic perturbations, reaching 15–17 cm. Contrary to barotropic, oscillations in baroclinic conditions are strongly pronounced in the deep-water areas of the Baltic Sea proper. Specific spatial patterns of amplitudes and phases of free barotropic and baroclinic sea level oscillations identified them as progressive–standing waves representing barotropic or baroclinic modes of gravity waves and topographic Rossby waves.

scholarly journals Spatio-temporal structure of Baltic free sea level oscillations in barotropic and baroclinic conditions from hydrodynamic modelling

2020 ◽  
Author(s):  
Eugeny A. Zakharchuk ◽  
Natalia Tikhonova ◽  
Elena Zakharova
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
Temporal Structure ◽  
Low Frequency ◽  
The Baltic Sea ◽  
Meteorological Forcing ◽  
Sea Level Oscillations ◽  
Spatio Temporal ◽  
The Baltic ◽  
Baroclinic Modes

Abstract. Free sea level oscillations in barotropic and baroclinic conditions were examined using numerical experiments based on a 3D hydrodynamic model of the Baltic Sea. In a barotropic environment, the highest amplitudes of free sea level oscillations are observed in the northern Gulf of Bothnia, eastern Gulf of Finland, and south-western Baltic Sea. In these areas, the maximum variance appears within the frequency range corresponding to periods of 13–44 hr. In a stratified environment, after the cessation of meteorological forcing, water masses relax to the equilibrium state in the form of mesoscale oscillations at the same frequencies as well as in the form of rapidly decaying low-frequency (seasonal) oscillations. The total amplitudes of free baroclinic perturbations are significantly larger than those of barotropic perturbations, reaching 15–17 cm. Contrary to barotropic, oscillations in baroclinic conditions are strongly pronounced in the deep-water areas of the Baltic Sea Proper. Specific spatial patterns of amplitudes and phases of free barotropic and baroclinic sea level oscillations identified them as progressive-standing waves representing barotropic or baroclinic modes of gravity waves and topographic Rossby waves.

scholarly journals Seasonal and Decadal Variations of the Variance of the Synoptic and Mesoscale Sea Level Variability in the Baltic Sea

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1785
Author(s):  
Igor Medvedev ◽  
Alisa Medvedeva
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
Absolute Maximum ◽  
The Baltic Sea ◽  
Sea Level Oscillations ◽  
Gulf Of Riga ◽  
Decadal Variations ◽  
The Baltic ◽  
High Coherence

The present study examines the seasonal and decadal changes of the variance of the synoptic (periods from 2 days to 30 days) and mesoscale (periods from 2 h to 2 days) sea level oscillations in the Baltic Sea. Long-term hourly sea level records were used at 12 tide gauges located in different parts of the sea. We used spectral analysis to estimate the variance for different time scales. The spectral density of sea level oscillations in the Baltic Sea has maximum values in winter when the cyclonic activity in the atmosphere is more intensive. The maximum variances of synoptic σsyn2  and mesoscale σmes2 sea level oscillations are observed in winter, except for the heads of the Gulf of Finland (Gorny Institute) and Gulf of Riga (Pärnu), where the absolute maximum of σsyn2 is reached in November. The variances σsyn2 and σmes2 from November to February are 2–3 and 5 times higher than in the summer. The values of σsyn2 and σmes2 are characterized by high correlation up to 0.7–0.75 with wind variations and atmospheric indices (NAO, AO, and SCAND) in winter and low correlation in summer. The zonal wind and σmes2 in Gorny Institute are characterized by wide areas of high coherence at periods of 0.7–4 years. At Gedser, σsyn2 decreased by 19%, and at Ratan it increased by 17% over 90 years. The values of σmes2 over 90 years increased by 32% at Klagshamn, 36% at Ratan, and up to 60% at Kungsholmsfort.

scholarly journals A Holocene relative sea-level database for the Baltic Sea

2021 ◽  
Vol 266 ◽  
pp. 107071
Author(s):  
Alar Rosentau ◽  
Volker Klemann ◽  
Ole Bennike ◽  
Holger Steffen ◽  
Jasmin Wehr ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
The Baltic Sea ◽  
Relative Sea Level ◽  
The Baltic

scholarly journals GIS analysis of effects of future Baltic Sea level rise on the island of Gotland, Sweden

2016 ◽  
Author(s):  
Karin Ebert ◽  
Karin Ekstedt ◽  
Jerker Jarsjö
Keyword(s):  
Baltic Sea ◽  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Aquifers ◽  
Salt Water ◽  
Global Perspective ◽  
Salt Water Intrusion ◽  
The Baltic Sea ◽  
Water Intrusion ◽  
The Baltic

Abstract. Future sea level rise as a consequence of global warming will affect the world's coastal regions. Even though the pace of sea level rise is not clear, the consequences will be severe and global. Commonly the effects of future sea level rise are investigated for relatively vulnerable development countries; however, a whole range of varying regions need to be considered in order to improve the understanding of global consequences. In this paper we investigate consequences of future sea level rise along the coast of the Baltic Sea island of Gotland, Sweden, with the aim to fill knowledge gaps regarding comparatively well-suited areas in non-development countries. We study both the quantity of loss of infrastructure, cultural and natural values for the case of a two metre sea level rise of the Baltic Sea, and the effects of climate change on seawater intrusion in coastal aquifers, causing the indirect effect of salt water intrusion in wells. We conduct a multi-criteria risk analysis by using Lidar data on land elevation and GIS-vulnerability mapping, which gives formerly unimaginable precision in the application of distance and elevation parameters. We find that in case of a 2 m sea level rise, 3 % of the land area of Gotland, corresponding to 99 km2, will be inundated. The features most strongly affected are items of touristic or nature values, including camping places, shore meadows, sea stack areas, and endangered plants and species habitats. In total, 231 out of 7354 wells will be directly inundated, and the number of wells in the high-risk zone for saltwater intrusion in wells will increase considerably. Some values will be irreversibly lost due to e.g. inundation of sea stacks and the passing of tipping points for sea water intrusion into coastal aquifers; others might simply be moved further inland, but this requires considerable economic means and prioritization. With nature tourism being one of the main income sources of Gotland, monitoring and planning is required to meet the changes. Seeing Gotland in a global perspective, this island shows that holistic multi-feature studies of future consequences of sea level rise are required, to identify overall consequences for individual regions.

Sea level variations in the coastal region from altimetry – Using optimal interpolation in the Baltic Sea for 3-day mean sea level from altimetry, tide gauge and model data

2021 ◽  
Author(s):  
Ida Margrethe Ringgaard ◽  
Jacob L. Høyer ◽  
Kristine S. Madsen ◽  
Adili Abulaitijiang ◽  
Ole B. Andersen
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
Temporal Resolution ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Coastal Region ◽  
Optimal Interpolation ◽  
The Baltic Sea ◽  
Spatial Coverage ◽  
The Baltic

<p>The rise and fall of the sea surface in the coastal region is observed closely by two different sources: tide gauges measure the relative sea level anomaly at the coast at high temporal resolution (minutes or hours) and satellite altimeters measure the absolute sea surface height of the open ocean along tracks multiple times a day. However, these daily tracks are scattered across the Baltic Sea with each track being repeated at a lower temporal resolution (days). Due to the inverse relationship between spatial and temporal coverage of the satellite altimetry data, gridded satellite altimetry products often prioritize spatial coverage over temporal resolution, thus filtering out the high sea level variability. In other words, the satellite data, and especially averaged products, often miss the daily sea level variability, such as storm surges, which is most important for all societies in the coastal region. To compensate for the sparse spatial coverage from satellite altimetry, we here present an experimental product developed as part of the ESA project Baltic+SEAL:  on a 3-day scale, the DMI Optimal Interpolation (DMI-OI) method is combined with error statistics from a storm surge model as well as 3-day averages from both tide gauge observations and satellite altimetry tracks to generate a gridded sea level anomaly product for the Baltic Sea for year 2017. The product captures the overall temporal evolution of the sea level changes well for most areas with an average RMSE wrt. tide gauge observations of 17.2 cm and a maximum of 34.2 cm. Thus, the 3-day mean gridded product shows potential as an alternative to monthly altimetry products, although further work is needed.</p>

scholarly journals Mechanisms of variability in decadal sea-level trends in the Baltic Sea over the 20th century

2017 ◽  
Vol 8 (4) ◽  
pp. 1031-1046 ◽  
Author(s):  
Sitar Karabil ◽  
Eduardo Zorita ◽  
Birgit Hünicke
Keyword(s):  
Regression Model ◽  
Baltic Sea ◽  
Sea Level ◽  
Atmospheric Circulation ◽  
Data Sets ◽  
Climatic Data ◽  
The Baltic Sea ◽  
Underlying Factor ◽  
Coastal Sea ◽  
The Baltic

Abstract. Coastal sea-level trends in the Baltic Sea display decadal-scale variations around a long-term centennial trend. In this study, we analyse the spatial and temporal characteristics of the decadal trend variations and investigate the links between coastal sea-level trends and atmospheric forcing on a decadal timescale. For this analysis, we use monthly means of sea-level and climatic data sets. The sea-level data set is composed of long tide gauge records and gridded sea surface height (SSH) reconstructions. Climatic data sets are composed of sea-level pressure, air temperature, precipitation, evaporation, and climatic variability indices. The analysis indicates that atmospheric forcing is a driving factor of decadal sea-level trends. However, its effect is geographically heterogeneous. This impact is large in the northern and eastern regions of the Baltic Sea. In the southern Baltic Sea area, the impacts of atmospheric circulation on decadal sea-level trends are smaller. To identify the influence of the large-scale factors other than the effect of atmospheric circulation in the same season on Baltic Sea sea-level trends, we filter out the direct signature of atmospheric circulation for each season separately on the Baltic Sea level through a multivariate linear regression model and analyse the residuals of this regression model. These residuals hint at a common underlying factor that coherently drives the decadal sea-level trends in the whole Baltic Sea. We found that this underlying effect is partly a consequence of decadal precipitation trends in the Baltic Sea basin in the previous season. The investigation of the relation between the AMO index and sea-level trends implies that this detected underlying factor is not connected to oceanic forcing driven from the North Atlantic region.

scholarly journals Sea Level Trends and Variability of the Baltic Sea From 2D Statistical Reconstruction and Altimetry

2019 ◽  
Vol 7 ◽  
Author(s):  
Kristine S. Madsen ◽  
Jacob L. Høyer ◽  
Ülo Suursaar ◽  
Jun She ◽  
Per Knudsen
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
The Baltic Sea ◽  
Statistical Reconstruction ◽  
The Baltic
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