scholarly journals Wave climate in the Arkona Basin, the Baltic Sea

Ocean Science ◽  
2012 ◽  
Vol 8 (2) ◽  
pp. 287-300 ◽  
Author(s):  
T. Soomere ◽  
R. Weisse ◽  
A. Behrens
Keyword(s):  
Baltic Sea ◽  
Wave Height ◽  
Wave Model ◽  
Wave Climate ◽  
Wind Fields ◽  
The Baltic Sea ◽  
Wave Heights ◽  
The Baltic ◽  
Basic Features

Abstract. The basic features of the wave climate in the Southwestern Baltic Sea (such as the average and typical wave conditions, frequency of occurrence of different wave parameters, variations in wave heights from weekly to decadal scales) are established based on waverider measurements at the Darss Sill in 1991–2010. The measured climate is compared with two numerical simulations with the WAM wave model driven by downscaled reanalysis of wind fields for 1958–2002 and by adjusted geostrophic winds for 1970–2007. The wave climate in this region is typical for semi-enclosed basins of the Baltic Sea. The maximum wave heights are about half of those in the Baltic Proper. The maximum recorded significant wave height HS =4.46 m occurred on 3 November 1995. The wave height exhibits no long-term trend but reveals modest interannual (about 12 % of the long-term mean of 0.76 m) and substantial seasonal variation. The wave periods are mostly concentrated in a narrow range of 2.6–4 s. Their distribution is almost constant over decades. The role of remote swell is very small.

scholarly journals Wave climatology in the Arkona Basin, the Baltic Sea

2011 ◽  
Vol 8 (6) ◽  
pp. 2237-2270 ◽  
Author(s):  
T. Soomere ◽  
R. Weisse ◽  
A. Behrens
Keyword(s):  
Baltic Sea ◽  
Wave Height ◽  
Significant Wave Height ◽  
Wave Climate ◽  
Extreme Wave ◽  
The Baltic Sea ◽  
Significant Wave ◽  
Wave Heights ◽  
The Baltic

Abstract. The basic features of the wave climate in the South-Eastern Baltic Sea are studied based on available long-term measurements and simulations. The analysis of average, typical and extreme wave conditions, frequency of occurrence of different wave parameters, variations in wave heights from weekly to decadal scales, etc., is performed based on waverider measurements at the Darss Sill since 1991. The measured climatology is compared against numerical simulations with the WAM wave model driven by downscaled reanalysis of wind fields for 1958–2002 and by adjusted geostrophic winds for 1970–2007. The wave climate in this region is typical for semi-enclosed basins of the Baltic Sea. The maximum wave heights are about half of those in the Baltic Proper. The overall reliably recorded maximum significant wave height HS =4.46 m occurred during a severe S-SW storm in 1993 when the 10-min average wind speed reached 28 m s−1. The long-term average significant wave height (0.75 m) shows modest interannual (about 12 % of the long-term mean) and substantial seasonal variation. The wave periods are mostly concentrated in a narrow range of 2.5–4 s and their distribution is almost constant over decades. The role of remote swell is very small. The annual wave properties show large interannual variability but no long-term trends in average and extreme wave heights can be observed.

scholarly journals Long-term spatial variations in the Baltic Sea wave fields

Ocean Science ◽  
2011 ◽  
Vol 7 (1) ◽  
pp. 141-150 ◽  
Author(s):  
T. Soomere ◽  
A. Räämet
Keyword(s):  
Baltic Sea ◽  
Spatial Variations ◽  
Extreme Wave ◽  
The Baltic Sea ◽  
Wave Fields ◽  
Wave Heights ◽  
The Baltic ◽  
Wave Properties ◽  
Sea Wave

Abstract. This study focuses on spatial patterns in linear trends of numerically reconstructed basic wave properties (average and extreme wave heights, wave periods) in the Baltic Sea under the assumption of no ice cover. Numerical simulations of wave conditions for 1970–2007, using the WAM wave model and adjusted geostrophic winds, revealed extensive spatial variations in long-term changes in both average and extreme wave heights in the Baltic Sea but almost no changes in the basinwide wave activity and wave periods. There has been a statistically significant decrease in the annual mean significant wave height by more than 10% between the islands of Öland and Gotland and in the southward sea area, and a substantial increase to the south-west of Bornholm, near the coast of Latvia, between the Åland Archipelago and the Swedish mainland, and between the Bothnian Sea and the Bothnian Bay. Variations in extreme wave heights (defined as the threshold for 1% of the highest waves each year) show similar patterns of changes. In several areas the trends in average and extreme wave heights are different. Such a complicated pattern of changes indicates that (i) different regions of the Baltic Sea basin have experienced widespread but essentially different changes in wind properties and (ii) many seemingly controversial trends and variations established in wave properties at different sites in the recent past may reflect the natural spatial variability in the Baltic Sea wave fields.

scholarly journals Effects of large-scale atmospheric circulation on the Baltic Sea wave climate: application of EOF method on multi-mission satellite altimetry data

2021 ◽  
Author(s):  
Fatemeh Najafzadeh ◽  
Nadezhda Kudryavtseva ◽  
Tarmo Soomere
Keyword(s):  
Baltic Sea ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Arctic Oscillation ◽  
Wave Climate ◽  
Altimetry Data ◽  
The Baltic Sea ◽  
Wave Heights ◽  
The Baltic ◽  
Satellite Altimetry Data

Abstract Wave heights in the Baltic Sea in 1992–2015 have predominantly increased in the sea's western parts. The linear trends in the winter wave heights exhibit a prominent meridional pattern. Using the technique of Empirical Orthogonal Functions (EOF) applied to the multi-mission satellite altimetry data, we link a large part of this increase in the wave heights with the climatic indices of the Scandinavian mode, North Atlantic Oscillation, and Arctic Oscillation. The winter trends show a statistically significant negative correlation (correlation coefficient –0.47±0.19) with the Scandinavian pattern and a positive correlation with the North Atlantic Oscillation (0.31±0.22) and Arctic Oscillation (0.42±0.20). The meridional pattern is associated with more predominant north-westerly and westerly winds driven by the Scandinavian and North Atlantic Oscillation, respectively. All three climatic indices show a statistically significant time-variable correlation with Baltic Sea wave climate during the winter season. When the Scandinavian pattern's influence is strong, North Atlantic and Arctic Oscillations' effect is low and vice versa. The results are backed up by simulations using synthetic data that demonstrate that the percentage of variance retrieved using EOF analysis from the satellite-derived wave measurements is directly related to the percentage of noise in the data and the retrieved spatial patterns are insensitive to the level of noise.

scholarly journals LONG-TERM RISE OF STORMINESS OF THE BALTIC SEA NEAR POLAND; POSSIBLE ORIGIN AND CONSEQUENCES

2011 ◽  
Vol 1 (32) ◽  
pp. 1
Author(s):  
Grzegorz Marcin Rozynski ◽  
Zbigniew Pruszak
Keyword(s):  
Baltic Sea ◽  
Wave Climate ◽  
Sandy Beaches ◽  
The Baltic Sea ◽  
Winter Storms ◽  
The North ◽  
The Baltic ◽  
The North Atlantic Oscillation ◽  
Autumn And Winter

Long-term growth of storminess of the Baltic Sea near Poland has been identified for autumn and winter months, particularly for January. This growth is concurrent with the increase of westerly waves in Jan., Feb. and Oct. A vivid relationship between the North Atlantic Oscillation and significant wave height Hs in Jan. suggests it can be a potential driver of storminess growth in that month. For Feb. this relationship is unstable; other months demonstrate no connection toward the NAO. The wave climate in January also exhibits a strong 8-year cycle, very likely to drive 8-year variations of shoreline position, detected previously at a study site. The influence of NAO may manifest an unfavorable regime change in which mightier winter storms will be mostly occurring above freezing in the absence of ice cover. Without that cover vulnerable sandy beaches will be exposed to accelerated erosion from direct and stronger wave attack.

A new wave hindcast for the North and Baltic Sea region using COSMO-REA6

2020 ◽  
Author(s):  
Nikolaus Groll
Keyword(s):  
Baltic Sea ◽  
Extreme Events ◽  
Wave Model ◽  
Wave Climate ◽  
Good Representation ◽  
Wind Fields ◽  
Wave Hindcast ◽  
The North ◽  
Atmospheric Observations ◽  
The Baltic

<p>Wave hindcasts are still required as improved knowledge of climate variables representing the present marine climate are needed. Most long regional wave hindcasts are driven by numerically downscaled wind fields from global reanalysis. Whereas this approach gives a good representation of the regional wave climate in general, there are some deficits in the characteristics of extreme events. Using regional atmospheric reanalysis, which assimilates atmospheric observations into the numerical model, a better description of extreme events is expected. The regional atmospheric reanalysis COSMO-REA6 from the German Weather Service (DWD) showed that it is capable of a better representation of atmospheric extreme events. For the new regional wave hindcast, covering the North Sea and the Baltic Sea, we use the COSMO-REA6 to force the wave model WAM. It is shown, that his new wind hindcast leads to an improved representation of extreme wave events compared to other regional wave hindcasts and thus supports an important contribution to the understanding of the wave climate of extremes and for the design phase of offshore activities.</p>

Abrupt changes in wave climate of regional seas caused by large-scale atmospheric forcing and teleconnections

2020 ◽  
Author(s):  
Nadia Kudryavtseva
Keyword(s):  
Baltic Sea ◽  
Caspian Sea ◽  
Large Scale ◽  
Wave Climate ◽  
The Baltic Sea ◽  
The Caspian Sea ◽  
Abrupt Changes ◽  
Wave Heights ◽  
The Baltic

<p>Climate warming is expected to change the functioning of regional seas substantially. However, it is still an open question how the global climate processes will affect in the future the regional seas, their wave climate, changes in the storm surges and, consequently, the coastal erosion, flooding risks, and coastal communities. In this study, we perform a detailed analysis of the wave climate of the Baltic Sea and the Caspian Sea based on the multi-mission satellite altimetry data in 1990 – 2017. The dataset of significant wave heights (SWH) from ten satellites was cross-validated against regional in situ buoy and echosounder measurements. In the Caspian Sea, due to the limited availability of the in-situ measurements, the satellite data were validated with visual wave measurements. After correction for systematic differences, the visual observations showed excellent correspondence with monthly averaged satellite data with a typical root mean square difference of 0.06 m. Even though several satellite pairs (ENVISAT/JASON-1, SARAL/JASON-2, ERS-1/TOPEX) exhibit substantial mutual temporal drift, and calm wave conditions are ignored, the overall picture is very consistent. The averaged over the whole basin annual mean SWH in the Baltic Sea shows an increase of 0.005 m/yr but no significant trend is detected in the Caspian Sea.</p><p>Interestingly, in both Baltic and Caspian seas, changes in the average SWH exhibit a strong spatial pattern. In the Baltic Sea, a meridional pattern is detected: an increase in the central and western parts of the sea and a decrease in the eastern part. This pattern has a timescale of ~13 yr. We also found a faster-varying region in the Baltic Proper where trends in the wave heights experience abrupt changes with a timescale of 3 years and show a strong relation to changes in the North Atlantic Oscillation. In the Caspian Sea, the wave height decreased by 0.019 ± 0.007 m/yr in the eastern segment of the central basin and by 0.04 ± 0.04 m/yr in the western segment of the southern basin when the other parts showed an increase of wave heights. These changes can be explained by an increase in the frequency of westerly winds at the expense of southerly winds. Analysing the changes in the atmospheric forcing we found that there is a cyclic behaviour with a timescale of ~12 years which result in abrupt changes in the wave climate every 12 years, causing the trends in different regions to reverse its sign.</p><p>We demonstrate that the impact on the coast and coastal community is caused by a complex chain of events, starting from changes in the wind direction due to large-scale atmospheric variability and atmospheric teleconnections, which create abrupt shifts in the wave climate of regional seas. We discuss that regional seas have a different response to the changing climate compared to the open ocean condition, which can lead to accelerated coastal erosion and a higher risk of flooding.</p>

scholarly journals Long-term spatial variations in the Baltic Sea wave fields

2010 ◽  
Vol 7 (6) ◽  
pp. 1889-1912
Author(s):  
T. Soomere ◽  
A. Räämet
Keyword(s):  
Baltic Sea ◽  
Spatial Variations ◽  
Extreme Wave ◽  
The Baltic Sea ◽  
Wave Fields ◽  
Wave Heights ◽  
The Baltic ◽  
Wave Properties ◽  
Sea Wave

Abstract. This study focuses on spatial patterns in linear trends of numerically reconstructed basic wave properties (average and extreme wave heights, wave period) in the Baltic Sea. Numerical simulations of wave conditions for 1970–2007, using the WAM wave model and adjusted geostrophic winds, revealed extensive spatial variations in long-term changes in both average and extreme wave heights in the Baltic Sea but almost no changes in the basinwide wave activity and wave periods. There has been a statistically significant decrease in the annual mean significant wave height by more than 10% between the islands of Öland and Gotland and in the southward sea area, and a substantial increase to the south-west of Bornholm, near the coast of Latvia, between Åland and the Swedish mainland, and between the Bothnian Sea and the Bothnian Bay. Variations in extreme wave heights (defined as the threshold for 1% of the highest waves each year) show similar patterns of changes. In several areas the trends in average and extreme wave heights are different. Such a complicated pattern of changes indicates that (i) different regions of the Baltic Sea basin have experienced widespread but essentially different changes in wind properties and (ii) many seemingly controversial trends and variations established in wave properties at different sites in the recent past may reflect the natural spatial variability in the Baltic Sea wave fields.

scholarly journals Satellite altimetry reveals spatial patterns of variations in the Baltic Sea wave climate

2016 ◽  
Author(s):  
Nadezhda Kudryavtseva ◽  
Tarmo Soomere
Keyword(s):  
Baltic Sea ◽  
Satellite Altimetry ◽  
Wave Climate ◽  
The Baltic Sea ◽  
Data Set ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
The Baltic ◽  
Satellite Altimetry Data

Abstract. The main properties of the climate of waves in the seasonally ice-covered Baltic Sea and its decadal changes since 1990 are estimated from satellite altimetry data. The data set of significant wave heights (SWH) from all existing ten satellites is cleaned and cross-validated against in situ buoy and echosounder measurements. Even though several satellite pairs (ENVISAT/JASON-1, SARAL/JASON-2, ERS-1/TOPEX) exhibit substantial mutual temporal drift, and calm situations are ignored, the overall picture is consistent. The annual mean SWH shows tentative increase 0.005 m/yr but higher quantiles behave in a cyclic manner with a timescale of 10–15 yr. Changes in the basin-wide average SWH have a strong meridional pattern: an increase in the central and western parts of the sea and decrease in the eastern part. This pattern is likely caused by a rotation of wind directions rather than by an increase in the wind speed.

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