final_program_abstracts[1]

11 IMSC Session Program
Long-term variability and changes in North East Atlantic and
European winter storminess
Friday - Poster Session 7
Paul M. Della-Marta and Malcolm R. Haylock
Partner Reinsurance Company, Switzerland
In this study we utilize the EMULATE daily mean sea level pressure (MSLP) dataset
to analyze the variability and change in North East Atlantic and European storminess
since 1880. We derive geostrophic wind speed from the MSLP and use this to define a
number of extreme wind indices (EWI), sensitive to different aspects of storm size
and intensity. We then apply extreme value analysis techniques to these storminess
series and investigate both long-term trends and variability of storminess as a function
of various covariates such as time and large-scale climate indices. Each daily
EMULATE MSLP field comes with an interpolation error field which we use to
estimate the error in the derived EWIs and the error in trend and variability analyses.
Results generally agree with previous studies which show that the there is no
significant trend in storminess since 1880 to present and that the storminess climate is
dominated by decadal and multi-decadal variability. However, a number of new
insights result from this analysis, such as a long-term decline in both storm frequency
and intensity from 1880~1910. Again, as in previous studies the 1990s are a decade
with frequencies and intensities of storminess that are comparable to those in the late
19th Century. Only when we consider western European land areas separately to the
North east Atlantic-European domain do we see that the decadal peak in storminess in
the 1990s as being unprecedented since 1880. Decadal modulation of the scale
parameter of the Generalized Pareto Distribution (GPD) shows that the 99th
percentile can change by up to 15% which we show has implications for the pricing of
wind storm related loss risk of loss.
Abstracts 305