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| Titel |
Extreme waves at Polar front of North Atlantic from 2000 to 2009 |
| VerfasserIn |
X. Feng, M. Tsimplis, M. Yelland |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250063614
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| Zusammenfassung |
| Surface elevation measurements obtained by a ShipBorne Wave Recorder (SBWR) at Station
Mike (66 N, 2 E) in Norwegian Sea are analysed. The data were collected by the Norwegian
Meteorological Institute (DNMI) during the period 2000-2009. The analysis is focused on
extreme wave records which have an Abnormality Index (AI) higher than 2. We also analyse
the frequency of occurrence of waves over 6 m in height which we call giant waves. We
found that the annual maximum of the extreme wave fails to reach up the annual maximum of
the giant wave in most of years. The largest extreme wave found was 22.0 m and occurred on
January 11st 2006 during a period of time when the significant wave height was
~10.7 m, while the largest giant height was 25.6 m and occurred on November
11st 2001 when the significant wave height was 15.2 m. We could not detect any
trends in the occurrence of extreme waves over the decade in question. However the
number of giant waves observed show an increasing tendency with time. The annual
mean of the extreme wave height increased from 4.6 m to 6.0 m between 2001
and 2009. During the same period the significant wave height Hs remained the
same.
Wind speed records from the same ship correlate well with the maximum wave height but
not with the AI which was also found to be independent of seasonality and corresponding
wind speed.
The annual mean of the extreme wave height was found to correlate with the winter NAO
which also correlates with Hs and Hmax. But it is ambiguous to say that AI correlates with
the seasonal NAO as well.
The suitability of the Rayleigh distribution to describe the probability of giant waves
under various AI conditions will also be discussed. |
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