Baltic Sea Level Research Articles

Comparison between the Baltic Sea and Irish Sea level of Cs-137 contamination on benthic, demersal and pelagic fish species

The Irish Sea and the Baltic Sea are nowadays still the two most Cs-137 contaminated Seas worldwide. However, the origins of this contaminations are completely different. While the Baltic Sea was unintentionally contaminated due to global fallout after the accident in the Chernobyl nuclear powerplant in 1986, the Irish sea was intentionally used for low level liquid radioactive waste discharges from the Sellafield nuclear reprocessing facility (called Windscale until 1981) between the 1950s and 1990s. Nowadays, more than 30 years later, it is still possible to detect these contaminations in fish, water and sediments of both seas. Since fish are an important part of the human diet, monitoring Cs-137 levels in fish is essential for assessing the potential radiation exposure to humans. In 2019 and 2020 two surveys were dedicated to study the current levels of radioactive contamination in fish species from both Seas. During both surveys, fish samples were collected and analysed by gamma spectrometry later on. The results show that the average Cs-137 activity in benthic, demersal and pelagic fish species from the Baltic Sea are 2.7, 4.6 and 4.2, respectively, times higher than the corresponding values of the Irish Sea. Based on this and two other comparisons, it is concluded that the Baltic Sea is the most contaminated with Cs-137.

Reviving the Aral Sea: A Hydro‐Eco‐Social Perspective

AbstractThe rapid shrinkage and salinization of the Aral Sea over the last few decades has precipitated an environmental disaster, with widespread implications for people whose livelihoods depend on it. Although debated extensively, few viable strategies have yet been identified for reviving the Aral Sea. Here, we propose a hydro‐eco‐social framework to develop a viable, sustainable solution and explore its feasibility to resolve the Aral Sea problem. Based on eco‐environmental indicators, we contend that it is feasible to raise the Aral Sea by 40 m above the Baltic Sea level, while maintaining salinity levels tolerable for aquatic organisms, simultaneously reducing sandstorm risk by 58%. Basin‐wide water balance under climate change scenarios shows that this level can be supported through management interventions that reduce water usage by 22.0–23.2 km3/year and ensure sufficient recharge into the lake, without compromising socio‐economic opportunities. To implement this solution, we propose establishing a socio‐ecologically aligned water governance network for basin‐scale water management that has potential application for other, similarly declining, major lake systems.

Seasonal fluctuations in Baltic sea level determined from satellite altimetry

This study used gridded daily satellite altimetry observations to investigate the spatial variability in the Baltic seasonal sea-level cycle and to assess the main factors that affected its interannual changes during the 1993–2018 period. In addition to the widely studied annual (Sa) and semiannual (Ssa) harmonics, the characteristics of higher frequency oscillations (terannual (three times a year or Sta) and quarterannual (four times a year or Sqa)) were investigated. We demonstrated that the Sa, Ssa, and Sqa harmonics can be reliably identified from gridded daily satellite altimetry data for all regions of the Baltic Sea. The Sta harmonic was reliably identified in all regions except the southeast part of the Baltic Proper and Danish Straits. Low amplitudes and large uncertainties caused by noise in the SLA time series impeded the Sta evaluation in these two regions. In the Baltic Sea, annual oscillations of sea level propagate from the southwest to northeast at a speed of 0.15–0.36 m/s, which is close to the theoretical phase speed of the baroclinic Kelvin wave. The Ssa, Sta, and Sqa oscillations did not demonstrate a statistically reliable spatial variability in the phase. In many regions of the Baltic Sea for the 1993–2018 period, a statistically significant (at the 95% level) increase of +1.3– + 2.2 mm/yr was observed for the amplitudes of the Sa harmonic, while for the amplitudes of the Ssa harmonic, a statistically significant decrease was detected. No statistically significant changes were observed in the amplitudes of the Sta and Sqa harmonics. Wind, atmospheric pressure, and water exchange with the North Sea correlated well with interannual changes in the sea-level seasonal cycle. The air temperature correlated well only with the Sa component. Precipitation, evaporation, and river input were not correlated with seasonal or interannual changes in the sea-level cycle.

Barystatic and steric sea level variations in the Baltic Sea and implications of water exchange with the North Sea in the satellite era

Satellite altimetry, satellite gravimetry, and in-situ subsurface salinity and temperature profiles are used to investigate the total, barystatic, and steric sea level variations in the Baltic Sea, respectively. To estimate the steric sea level, the density variations are weighted in deeper layers to prevent overestimation of their contribution. We show that the sum of barystatic and steric components exhibits excellent cross correlation (0.9) with satellite altimetry sea level variations and also explains up to 84% of total signal variability from 2002 to 2019. Considering the dominance of barystatic sea level variations in the basin and the limitation of satellite gravimetry in resolving the mass change in water-land transition zones (known as the leakage problem), the mismatch is likely attributed to the inadequate accuracy of the barystatic datasets. The total sea level and its contributors are further decomposed into seasonal, interannual, and decadal temporal components. It is shown that despite its insignificant contributions to seasonal and interannual changes, the steric sea level plays an important role in decadal variations. Additionally, we show that the interannual variations of the barystatic sea level are governed by the North Atlantic Oscillation in the basin. The sea level variation in the North Sea is also examined to deduce the water exchange patterns on different time scales. A drop in the North Sea level can be seen from 2005 to 2011 which is followed by the Baltic Sea level with a ~3-year lag, implying the outflow from the Baltic Sea to the North Sea.

Wavelet Analysis of The Influence of Longitude on the Height of the Capitals of the Subjects of The Russian Federation

City centers appeared at the time of their emergence and therefore have, in many cases, coordinates unchanged for centuries. Cities arose in the best geomorphological and climatic conditions. 86 asymmetric wavelets of the influence of east longitude on the height of the centers of the capitals of the subjects of the federation above the Baltic Sea level were obtained. The high accuracy of model-ing allows us to make a conclusion about the quantum certainty of the behavior of the population in urbanization.

Paleolimnological changes in the composition of diatom complexes in the context of the Holocene Baltic Sea transgressions (Lake Zaychikhinskoye)

Abstract. The study examines the issues of changes in the level of the Baltic Sea over the past 10 thousand years. According to the data of domestic and foreign authors on time, there is no unambiguous data on the duration and level of littorina transgression, which is considered the largest during the Holocene period. By the research, with the financial support of the RFBR grant-graduate students No. 20-35-90089, studies of bottom sediments of lakes Goluboye, Bolshoye Molochnoye and Zaychikhinskoye are being carried out. The report presents the results of the diatom analysis of Lake Zaychikhinskoye. The main stages of the lake s development are determined, it is established that in the early Holocene its development was determined by the transgressive-regressive stages of the Baltic. At the initial stage, the reservoir was part of a deep oligotrophic Ancylus lake. During the littorina transgression, the Baltic Sea level most likely did not rise to lake level in this area.

Multidecadal Sea Level Variability in the Baltic Sea and Its Impact on Acceleration Estimations

Multidecadal sea level variation in the Baltic Sea is investigated from 1900 to 2020 deploying satellite and in situ datasets. As a part of this investigation, nearly 30 years of satellite altimetry data are used to compare with tide gauge data in terms of linear trend. This, in turn, leads to validation of the regional uplift model developed for the Fennoscandia. The role of North Atlantic Oscillation (NAO) in multidecadal variations of the Baltic Sea is also analyzed. Although NAO impacts the Baltic Sea level on seasonal to decadal time scales according to previous studies, it is not a pronounced factor in the multidecadal variations. The acceleration in the sea level rise of the basin is reported as statistically insignificant in recent studies or even decelerating in an investigation of the early 1990s. It is shown that the reason for these results relates to the global warming hiatus in the 1950s−1970s, which can be seen in all eight tide gauges used for this study. To account for the slowdown period, the acceleration in the basin is investigated by fitting linear trends to time spans of six to seven decades, which include the hiatus. These results imply that the sea level rise is accelerated in the Baltic Sea during the period 1900–2020.

Sea level dynamics and coastal erosion in the Baltic Sea region

Abstract. There are a large number of geophysical processes affecting sea level dynamics and coastal erosion in the Baltic Sea region. These processes operate on a large range of spatial and temporal scales and are observed in many other coastal regions worldwide. This, along with the outstanding number of long data records, makes the Baltic Sea a unique laboratory for advancing our knowledge on interactions between processes steering sea level and erosion in a climate change context. Processes contributing to sea level dynamics and coastal erosion in the Baltic Sea include the still ongoing viscoelastic response of the Earth to the last deglaciation, contributions from global and North Atlantic mean sea level changes, or contributions from wind waves affecting erosion and sediment transport along the subsiding southern Baltic Sea coast. Other examples are storm surges, seiches, or meteotsunamis which primarily contribute to sea level extremes. Such processes have undergone considerable variation and change in the past. For example, over approximately the past 50 years, the Baltic absolute (geocentric) mean sea level has risen at a rate slightly larger than the global average. In the northern parts of the Baltic Sea, due to vertical land movements, relative mean sea level has decreased. Sea level extremes are strongly linked to variability and changes in large-scale atmospheric circulation. The patterns and mechanisms contributing to erosion and accretion strongly depend on hydrodynamic conditions and their variability. For large parts of the sedimentary shores of the Baltic Sea, the wave climate and the angle at which the waves approach the nearshore region are the dominant factors, and coastline changes are highly sensitive to even small variations in these driving forces. Consequently, processes contributing to Baltic sea level dynamics and coastline change are expected to vary and to change in the future, leaving their imprint on future Baltic sea level and coastline change and variability. Because of the large number of contributing processes, their relevance for understanding global figures, and the outstanding data availability, global sea level research and research on coastline changes may greatly benefit from research undertaken in the Baltic Sea.

ПРИРОДНЫЕ ОСОБЕННОСТИ И АНТРОПОГЕННЫЕ ФАКТОРЫ ФОРМИРОВАНИЯ ЭКОСИСТЕМ КУРШСКОЙ КОСЫ

The article shows history of the unique eolian coastal-marine complexes of the Curonian Spit development. The leading role of the Baltic Sea sea level fluctuations and wind activity in the formation of the spit is emphasized. Attention is paid to the territory development resuted in almost total destruction of the vegetion cover and transformation of the Curonian Spit into a sandy desert by the end of the 18th century. A variety of nature conservation measures to create the cultural landscape of the peninsula is highlighted. A modern landscape structure of the Curonian Spit is presented. The spit has the status of a National Park and is included in the UNESCO World Heritage List.

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

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.

Influence of macroscale and regional circulation patterns on low- and high-frequency sea level variability in the Baltic Sea

The atmospheric impact on sea level variability in the Baltic Sea on different time scales was investigated. The Northern Hemisphere teleconnection patterns, namely, the North Atlantic Oscillation (NAO), Arctic Oscillation (AO) and Scandinavia (SCAND) patterns, were employed, and a strong but non-stationary relationship was found. The SCAND appeared to be most relevant to the mean monthly Baltic Sea level variations throughout the year. A negative correlation indicates that a cyclonic centre over Scandinavia in the negative phase of SCAND enhances western circulation, which then triggers water inflow through the Danish straits. The AO annular mode reveals a positive and slightly stronger relationship with the Baltic Sea level than the NAO. The rapid increases in the Baltic Sea level recognized in this study, namely, those exceeding 24 cm within a 5-day period, mainly occur in the cold season. These increases are associated with the development of specific synoptic conditions in the Euro-Atlantic region, characterized by a shift from high to low pressure over Europe and a rapid increase in the pressure gradient during the week preceding the sea level rise. Rapid increases are associated with cyclones coming from the North Atlantic, which move 1500–2000 km during the week preceding the strong rise of the Baltic waters. The cyclone tracks may be shifted north or south, while the final position is over the Norwegian Sea.

Influence of Baltic Sea level rise on historic and cultural heritage of Russia

Influence of Baltic Sea level rise on historic and cultural heritage of Russia

Spatial Structure and Propagation of the Neva Flood Waves

The analysis of the results of numerical hydrodynamic modeling of water level and current fluctuations of the Baltic Sea in the periods of floods in the Finland and Riga gulfs is carried out. It is shown that due to the considerable isolation of the sea a great influence on the dynamics of flood waves have the processes they reflect, resulting in a generated progressive-standing waves. During a especially dangerous sea level rise on January 9, 2005, the flood wave had a period of about 40–42 hours. This period turned out to be close to the 41-hour period of the Baltic Sea, distinguished on the basis of an analysis of the results of numerical hydrodynamic modeling of free Baltic Sea level oscillations. The spatial structure of the level field for eigenoscillations with a period of 41 hours allows them to be identified as multinodal progressive-standing waves, characterized by a large number of amphidromic systems and antinodes. One of the most pronounced antinodes of eigenoscillations with a period of 41 hours is in the Neva Bay of the Gulf of Finland.

Low-Frequency Baltic Sea Level Spectrum

This study examines the Baltic sea level spectrum in the interval of periods from a few months to decades. Effective statistical methods of time series analysis have been applied to the long-term data from 36 tide gauges in the Baltic Sea, the Danish straits, and southeastern part of the North Sea to examine the character of low-frequency sea level variability. Using the spectral and wavelet analyses, we obtained estimates of the magnitudes of the main long period components of the sea level oscillations with periods of 8.4, 7.76, 6.16, 2.5, 1.7, 1.2 yr and discussed their possible origin. The peak with a period of 255 days is revealed in both the sea level spectra of the Baltic Sea and in the spectra of atmospheric processes. It is more pronounced in the air pressure variations from atmospheric reanalyses, especially ERA-Interim and NCEP/CFSR. Wavelet analysis revealed high coherence between the sea level oscillations at different stations and also with the zonal wind component. The result of the study shows that the low-frequency sea level variability in the Baltic Sea is highly correlated with the zonal wind variations over the extensive shallow-water areas of the sea.

Characteristics of Sediments in a Changing Environmental Conditions in Vistula Lagoon (Poland)

The Vistula Lagoon has been evolving since its formation in the late Atlantic period. At the beginning, the changes were mainly driven by the stabilization of the Baltic Sea level, and the development of hydrographic network. Later on, anthropogenic activities have become an important factor. Hydrotechnical works conducted at the turn of the 20th century, aimed at regulating the outflow of the Vistula River waters, have significantly limited the riverine input into the lagoon. In the past, the Vistula Lagoon contained freshwater and was constantly filing with sediments that made the basin shallow. With time, the lagoon has filled with brackish water, while its area became subjected to strong interactions between the driving forces of marine and terrestrial origin. As a result, the regime of sedimentation processes in the lagoon have been changed. The interpretation of sedimentation conditions for clastic sediments was based on the analysis of grain-size parameters that had been determined on the samples of bottom sediments and suspension collected in November 2016. The obtained results were compared to the pertinent data on bottom sediments collected by the Polish Geological Institute National Research Institute in 1994. Significant contrasts in particle size distributions were found. Also, the conducted study allowed the determination of underlying causes of these changes. Due to the shallow depth of the Vistula Lagoon, the sedimentation processes in this basin are significantly influenced by resuspension phenomenon. Resuspension is responsible for the differentiation and redistribution of sediment that originates from various sources, on the bottom of the basin. The process takes place in shallower areas, but this study indicates that its effectiveness increases in the deeper areas of the lagoon, which manifests itself in the replacement of clayey silt with silt. In connection with the plans of the Polish side of the cross-cutting of the Vistula Spit, the sedimentation conditions of Vistula Lagoon will be changed.

The evolution and disappearance of “false delta” multi-channel systems in postglacial areas (Central Europe)

Abstract River deltas are complex aggradational systems preserving the history of their evolution in the depositional record. While coastal deltas are extensively studied, little is known about “false delta”, multi-channel systems situated at a certain distance from the sea. The term “false delta” is used here in reference to a system of bifurcating alluvial channels influenced by sea level changes, and variations in discharge and sediment delivery. These interactions resulted in the formation of a multitude of channel planforms, and a “delta-like” fluvial landscape. We present the first study that aims to determine the influence of downstream controls (sea level changes) and upstream controls (discharge and sediment delivery) on the evolution of a “false delta” multi-channel system in the postglacial areas of central Europe. Our study is based on geophysical, geological and remote sensing methods, alongside radiocarbon dating (AMS–accelerator mass spectrometry). We use the example of a “delta-like” system of palaeochannels that connected the Obra and Odra Rivers (central Europe, Poland). The “false delta” formed within an ice-marginal valley by the activity of large-scale meandering channels in the Late Glacial period. Between 13,300 and 11,200 cal. BP, a transition to an anabranching and sinuous planform was caused by the coupled effects of a lowering Baltic Sea level, an increase in flood frequency and in sediment delivery. During this period, bifurcation began conveying 30% of the flow through a former subglacial tunnel to the Warta River. The Holocene evolution of this multi-channel system was driven by the interplay of successive sea level rise and sediment delivery from the middle Obra valley, and former subglacial tunnels. The upstream controls dominated during the last 4400 cal. BP, and were enhanced by mill constructions and deforestation in the last millennium. The false delta “disappeared” in the 18th century owing to a 63% decrease in flows. Based on these findings, we propose a model describing the evolution of “false delta” river systems in postglacial areas of Europe. Three stages of evolution are identified: i) formation by high flows, ii) sustaining the flow through particular branches in conditions of dominating deposition, and iii) discontinuation of the false deltas by hydro technical works. The model can be extrapolated to other areas in postglacial Europe and North America after refinement by further field studies.

Geocentric Baltic Sea level changes along the southern coastline

Sea level is a unique indicator in climate impact studies on any changes on the surface of the Earth. Traditionally, tide gauges allow observation of relative (relative to land) sea level changes at specific locations with a high resolution in time. Common method of sea level determination in XXI century is the combination of tide gauge observations with satellite observation data. So determined sea level changes are absolute changes and they are referred to the beginning of the ITRF system.Geocentric changes in the Baltic Sea level are monitored, inter alia, by the SONEL network. This network system does not include the southern coast of the Baltic Sea. The aim of this work is to fill this gap and to compute geocentric changes in the Baltic Sea at the stations: Hel, Władysławowo, Łeba, Ustka, Kołobrzeg, Świnoujście.The tide gauge data needed for the analysis were made available by the Institute of Meteorology and Water Management and the GNSS data was taken from web page Nevada Geodetic Laboratory. The analysis of the time series of tide gauge and GNSS observations was carried out using the TSAnalyzer software. We assumed that GNSS and tide gauge series have a seasonal signal (annual plus semi-annual) and a trend. First the outliers were removed from observation, then the jumps were viewing. The trend, annual and semi-annual terms were calculated for GNSS and tide gauge series.The results of the work are calculated geocentric changes in the Baltic Sea level along southern coast and they are at a level of 0.3 mm/year except Ustka where it reach value 4.68 mm/year.

Baltic Sea level changes from satellite altimetry data based on the OptD metod

Baltic Sea level changes from satellite altimetry data based on the OptD metod

Calculation Method of Maximum Snow Load in Depressions Located on the Territory of Transcarpathian Region According to the Simplified Formulae

The snow load in depressions has been actually studied partially according to the basic data of the snow cover in the III climatic zone of the Building Code of Ukraine, later on – according to the observed precipitation at meteorological observing stations, and over the last years – according to the observations at the meteorological observing stations. There have been used in this paper the observation data within the period from 1948 to 2015 with maximum snow cover depths and snow density in the depressions at 9 meteorological observing stations of Transcarpathian region (Ukraine) with the establishment of the simplified formulae of the average snow loads for the depression contour heights. It is enough to have the height of the point above the Baltic sea level to define maximum snow parameters in depressions: snow cover depth, snow density, snow load on the horizontal surface.

Spatial and Temporal Features of Synoptic and Mesoscale Variability of the Baltic Sea Level

The spatial and temporal features of synoptic and mesoscale variability of the Baltic Sea level are studied using long-term hourly data. The spectral analysis revealed significant difference in the structure of the sea level spectra between the Gulf of Bothnia and the Gulf of Finland. The maximum variance of the synoptic sea level variability is observed at the head of the Gulf of Bothnia and in the southwestern part of the Baltic Sea, whereas the maximum variance of mesoscale variability is registered at the head of the Gulf of Finland and in the southwestern part of the sea. The minimum variance of synoptic sea level variability was observed in the Gulf of Bothnia in the 1950s–1960s, and the maximum was recorded at the beginning and at the end of the 20th century. The series of interdecadal variability of synoptic sea level fluctuations have a weak negative trend up to −0.11 cm2/year in Kungsholmfrost. A significant qualitative and quantitative correlation was detected between the interannual variability of variance of mesoscale sea level variations in the Gulf of Finland (Gornyi Institut) and the Gulf of Riga (Parnu) and the interannual variability of the NAO index.