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 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.

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 LONG TERM EVOLUTION OF BALTIC SEA SANDY BEACH FORCED BY WINTER NORTH ATLANTIC OSCILLATION (NAOWI)

2012 ◽  
Vol 1 (33) ◽  
pp. 70
Author(s):  
Rozynski Grzegorz ◽  
Piotr Szmytkiewicz
Keyword(s):  
Baltic Sea ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Sandy Beach ◽  
Wave Climate ◽  
Periodic Patterns ◽  
Strong Argument ◽  
Shoreline Evolution ◽  
The Baltic

The study examines a hypothesis on the coupling between Winter North Atlantic Oscillation (NAOWI) and hydro- and morphodynamics of a sandy beach with multiple bars, situated at a Baltic Sea coastal segment in northern Poland. Identification of coincident long-term periodic patterns of shoreline variability and NAOWI is a strong argument for the existence of such a coupling, because the Baltic Sea is purely non-tidal and shoreline evolution is driven entirely by waves. Interestingly, similar periodic patterns were also found in the reconstructed long-term winter wave climate (hourly retrieved significant wave height between 1958 – 2001). Therefore, the hypothesis received a strong and comprehensive statistical footing. It highlights the fact that long-term periodic changes in winter energy fluxes from air through waves to the beach remain imprinted in shoreline evolution. Hence, any climate change driven modifications of global meteorological patterns, such as NAOWI, may have vital implications for Baltic Sea beaches in coming decades.

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 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.

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