Extremes and Decadal Variations in the Baltic Sea Wave Conditions

Soomere, Tarmo

doi:10.1007/978-3-319-21575-4_7

Cited by 6 publications

(5 citation statements)

References 59 publications

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“…A decrease is observed in many locations near the eastern coast of the sea. Even though these changes are not directly comparable with the outcome of numerical simulations for single decades (Soomere and Räämet, 2014), they show a pattern that differs radically from the usual perception of a gradual increase in the wave activity in the eastern Baltic Sea (Hünicke et al, 2015) and also has a clear mismatch with trends established for 1970-2005(Soomere and Räämet, 2011. ).…”

Section: Testing the Presence Of Trendscontrasting

confidence: 63%

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

Kudryavtseva

Soomere

2016

Preprint

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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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Section: Testing the Presence Of Trendscontrasting

confidence: 63%

“…Simulations based on geostrophic winds indicated a complicated spatial pattern of statistically significant trends in the SWH in 1970-2007(Soomere and Räämet, 2011. The largest increase in the SWH was identified near the Latvian coast of the Baltic Sea and a steep decrease in an area to the south of Gotland.…”

Section: Testing the Presence Of Trendsmentioning

confidence: 98%

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

Kudryavtseva

Soomere

2016

Preprint

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“…Differently from the Baltic Sea where the changes in the average and extreme wave heights have the same spatial pattern (Soomere & Räämet 2014;Soomere 2016), some changes in the severest wave conditions in the Caspian Sea are inconsistent with similar changes in the mean wave properties. The above has shown that the mean wave heights increased in region IV, but the 99th percentile shows an apparent decrease with time ( Fig.…”

Section: Resultsmentioning

confidence: 86%

Spatial variations in the Caspian Sea wave climate in 2002–2013 from satellite altimetry

Kudryavtseva¹,

Kussembayeva²,

Rakisheva³

et al. 2019

Estonian J. Earth Sci.

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The core properties of the wave climate and its changes in the Caspian Sea are established in terms of the annual mean significant wave height and its regional changes in 2002-2013 based on the outcome of the satellite altimetry mission JASON-1. Remotely estimated wave heights are validated against properties of the empirical distribution of instrumentally measured wave heights in the southern Caspian Sea and monthly averages of visually observed wave heights at three locations. A correction for systematic differences leads to very good correspondence between monthly averaged in situ and satellite data with a typical root mean square difference of 0.06 m.The average significant wave height in the Caspian Sea is 0.5-0.7 m in the northern basin of the sea, around 1.2 m in large parts of the central and southern basins and reaches up to 1.8 m in the northern segment of the central basin. The basin-wide average wave intensity varied insignificantly in the range of 1.02-1.14 m in 2002-2013. These estimates overestimate the wave heights by about 30% because low wave conditions are ignored. Substantial and statistically significant changes in the wave height occurred in certain areas. 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. These changes can be explained by an increase in the frequency of westerly winds at the expence of southerly winds. Both basin-wide and regional extreme wave heights exhibit large interannual variations but do not show any significant trend. The patterns of changes in mean and extreme wave height are different. The average wave height has increased while the extreme wave height has decreased in the eastern segment of the southern basin.

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“…These levels of the backscatter coefficient correspond to low wind speeds of < 2.5 m/s. As the typical significant wave heights of the Baltic Sea are around 1 m (Tuomi et al 2011;Soomere 2016), potential errors larger than half of this value (> 0.5 m) are generally unacceptable.…”

Section: Cross-matches Between Satellite and Buoy Measurementsmentioning

confidence: 99%

“…The complexity of wave fields and particularly their spatial and temporal variations in the Baltic Sea extend far beyond the typical features of surface wave climate in water bodies of comparable size (Leppäranta & Myrberg 2009;Soomere 2016). Owing to the relatively small size of the sea, the wave fields mainly follow changes in the wind properties and at times reveal even regime shifts .…”

Section: Introductionmentioning

confidence: 99%

Validation of the multi-mission altimeter wave height data for the Baltic Sea region

Kudryavtseva¹,

Soomere²

2016

Estonian J. Earth Sci.

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We present a complete cross-validation of significant wave heights (SWH) extracted from altimetry data from all ten existing satellites with available in situ (buoy and echosounder) wave measurements for the Baltic Sea basin. The main purpose is to select an adequate altimetry data subset for a subsequent evaluation of the wave climate. The satellite measurements with the backscatter coefficients > 13.5 cdb, errors in the SWH normalized standard deviation > 0.5 m and snapshots with centroids closer than 0.2° to the land are not reliable. The ice flag usually denotes the ice concentration of > 50%. The presence of ice affects the SWH data starting from concentrations 10%, but substantial effects are only evident for concentrations > 30%. The altimetry data selected based on these criteria have very good correspondence with in situ data, except for GEOSAT Phase 1 data (1985)(1986)(1987)(1988)(1989) that could not be validated. The root-mean-square difference of altimetry and in situ data is in the range of 0.23-0.37, which is significant for the Baltic Sea, compared with an average wave height of ~ 1 m. The bias for CRYOSAT-2, ERS-2, JASON-1/2 and SARAL data is below 0.06 m. The ENVISAT, ERS-1, GEOSAT and TOPEX satellites revealed larger biases up to 0.23 m. The SWH time series from several satellite pairs (ENVISAT/JASON-1, SARAL/JASON-2, ERS-1/TOPEX) exhibit substantial mutual temporal drift and part of them evidently are not homogeneous in time. A new high-resolution SWH data set from the SARAL satellite reveals a very good correspondence with the in situ data and with the data stream from previous satellites.

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Extremes and Decadal Variations in the Baltic Sea Wave Conditions

Cited by 6 publications

References 59 publications

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

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

Spatial variations in the Caspian Sea wave climate in 2002–2013 from satellite altimetry

Validation of the multi-mission altimeter wave height data for the Baltic Sea region

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