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| Titel |
Bayesian trend analysis of extreme wind using observed and hindcast series off the Catalan coast, NW Mediterranean Sea |
| VerfasserIn |
M. I. Ortego, J. J. Egozcue, R. Tolosana-Delgado |
| 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 Sciences ; 14, no. 9 ; Nr. 14, no. 9 (2014-09-10), S.2387-2397 |
| Datensatznummer |
250118658
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| Publikation (Nr.) |
 copernicus.org/nhess-14-2387-2014.pdf |
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| Zusammenfassung |
It has been suggested that climate change might modify the occurrence rate
and magnitude of large ocean-wave and wind storms. The hypothesised reason is
the increase of available energy in the atmosphere–ocean system. Forecasting
models are commonly used to assess these effects, given that good-quality
data series are often too short. However, forecasting systems are often tuned
to reproduce the average behaviour, and there are concerns on their relevance
for extremal regimes. We present a methodology of simultaneous analysis of
observed and hindcast data with the aim of extracting potential time drifts
as well as systematic regime discrepancies between the two data sources. The
method is based on the peak-over-threshold (POT) approach and the generalized
Pareto distribution (GPD) within a Bayesian estimation framework. In this
context, storm events are considered points in time, and modelled as
a Poisson process. Storm magnitude over a reference threshold is modelled
with a GPD, a flexible model that captures the tail behaviour of the
magnitude distribution.
All model parameters, i.e. shape and location of the magnitude GPD and the
Poisson occurrence rate, are affected by a trend in time. Moreover, a
systematic difference between parameters of hindcast and observed series is
considered. Finally, the posterior joint distribution of all these trend
parameters is studied using a conventional Gibbs sampler. This method is
applied to compare hindcast and observed series of average wind speed at
a deep buoy location off the Catalan coast (NE Spain, western Mediterranean;
buoy data from 2001; REMO wind hindcasting from 1958 on). Appropriate scale
and domain of attraction are discussed, and the reliability of trends in time
is addressed. |
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