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Titel |
Freak waves of different types in the coastal zone of the Baltic Sea |
VerfasserIn |
I. Didenkulova, C. Anderson |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1561-8633
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Digitales Dokument |
URL |
Erschienen |
In: Natural Hazards and Earth System Science ; 10, no. 9 ; Nr. 10, no. 9 (2010-09-30), S.2021-2029 |
Datensatznummer |
250008414
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Publikation (Nr.) |
copernicus.org/nhess-10-2021-2010.pdf |
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Zusammenfassung |
We present a statistical analysis of freak waves1 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.
1 taken to
be waves whose height is 2 or more times greater than the
significant wave height |
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