Freak waves of different types in the coastal zone of the Baltic Sea

We present a statistical analysis of freak waves<sup>1</sup> measured during the 203 h of observation on sea surface elevation at a location in the coastal zone of the Baltic Sea (2.7 m depth) during June–July 2008. The dataset contains 97 freak waves occurring in both ca...

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Main Authors: I. Didenkulova, C. Anderson
Format: Article
Language:English
Published: Copernicus Publications 2010-09-01
Series:Natural Hazards and Earth System Sciences
Online Access:http://www.nat-hazards-earth-syst-sci.net/10/2021/2010/nhess-10-2021-2010.pdf
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author I. Didenkulova
C. Anderson
author_facet I. Didenkulova
C. Anderson
author_sort I. Didenkulova
collection DOAJ
description We present a statistical analysis of freak waves<sup>1</sup> measured during the 203 h of observation on sea surface elevation at a location in the coastal zone of the Baltic Sea (2.7 m depth) during June–July 2008. The dataset contains 97 freak waves occurring in both calm and stormy weather conditions. All of the freak waves are solitary waves, 63% of them having positive shape, 17.5% negative shape and 19.5% sign-variable shape. It is suggested that the freak waves can be divided into two groups. Those of the first group, which includes 92% of the freak waves, have an amplification factor (ratio of freak wave height to significant wave height) which does not vary from significant wave height and has values largely within the range of 2.0 to 2.4; while for the second group, which contain the most extreme freak waves, amplification factors depend strongly on significant wave height and can reach 3.1. Analysis based on the Generalised Pareto distribution is used to describe the waves of the first group and lends weight to the identification of the two groups. It is suggested that the probable mechanism of the generation of freak waves in the second group is dispersive focussing. The time-frequency spectra of the freak waves are studied and dispersive tracks, which can be interpreted as dispersive focussing, are demonstrated. <br><br> <sup>1</sup> taken to be waves whose height is 2 or more times greater than the significant wave height
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spelling doaj.art-f7096aa08b294b7da35e5f95eb2afd482022-12-22T02:19:15ZengCopernicus PublicationsNatural Hazards and Earth System Sciences1561-86331684-99812010-09-011092021202910.5194/nhess-10-2021-2010Freak waves of different types in the coastal zone of the Baltic SeaI. DidenkulovaC. AndersonWe present a statistical analysis of freak waves<sup>1</sup> measured during the 203 h of observation on sea surface elevation at a location in the coastal zone of the Baltic Sea (2.7 m depth) during June–July 2008. The dataset contains 97 freak waves occurring in both calm and stormy weather conditions. All of the freak waves are solitary waves, 63% of them having positive shape, 17.5% negative shape and 19.5% sign-variable shape. It is suggested that the freak waves can be divided into two groups. Those of the first group, which includes 92% of the freak waves, have an amplification factor (ratio of freak wave height to significant wave height) which does not vary from significant wave height and has values largely within the range of 2.0 to 2.4; while for the second group, which contain the most extreme freak waves, amplification factors depend strongly on significant wave height and can reach 3.1. Analysis based on the Generalised Pareto distribution is used to describe the waves of the first group and lends weight to the identification of the two groups. It is suggested that the probable mechanism of the generation of freak waves in the second group is dispersive focussing. The time-frequency spectra of the freak waves are studied and dispersive tracks, which can be interpreted as dispersive focussing, are demonstrated. <br><br> <sup>1</sup> taken to be waves whose height is 2 or more times greater than the significant wave heighthttp://www.nat-hazards-earth-syst-sci.net/10/2021/2010/nhess-10-2021-2010.pdf
spellingShingle I. Didenkulova
C. Anderson
Freak waves of different types in the coastal zone of the Baltic Sea
Natural Hazards and Earth System Sciences
title Freak waves of different types in the coastal zone of the Baltic Sea
title_full Freak waves of different types in the coastal zone of the Baltic Sea
title_fullStr Freak waves of different types in the coastal zone of the Baltic Sea
title_full_unstemmed Freak waves of different types in the coastal zone of the Baltic Sea
title_short Freak waves of different types in the coastal zone of the Baltic Sea
title_sort freak waves of different types in the coastal zone of the baltic sea
url http://www.nat-hazards-earth-syst-sci.net/10/2021/2010/nhess-10-2021-2010.pdf
work_keys_str_mv AT ididenkulova freakwavesofdifferenttypesinthecoastalzoneofthebalticsea
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