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Extreme value statistics for North Atlantic cyclones Cover

Extreme value statistics for North Atlantic cyclones

Open Access
|Jan 2010

Abstract

Extremes of the cyclone intensity measures geopotential height (ɀ1000), mean horizontal gradient (Δɀ), cyclone depth (D), and relative vorticity (ζ850), are analysed in re-analysis data (ERA40) and model simulations (ECHAM5/MPIOM) in the North Atlantic region for extended winter seasons. Generalized Pareto distributions (GPD) are estimated for model validation and climate change assessment. Covariates, linear trend and North Atlantic Oscillation (NAO) are included to analyse the dependancies of the extremes.

In ERA40 no significant linear trend can be detected, while evidence for a NAO impact on ɀ1000, Δɀ and ζ850 extremes is found. Model validation yields good agreement with consistent scale and shape, but a shift to lower values is notable. Like in ERA40 no trend is found in the simulation. The evidence for an NAO impact on cyclone extremes is less corroborated in the simulation, pointing to sample size effects.

In the warmer climate scenario (A1BS) extreme value statistics shows an intensification for all variables. Significant differences in GPD are obtained through testing for lower (higher) parameters. In contrast, considering all cyclones an increase is only present for ɀ1000, while a decrease is found for Δɀ and ζ850 and no change for D.

Language: English
Page range: 347 - 360
Submitted on: Aug 7, 2009
Accepted on: Mar 18, 2010
Published on: Jan 1, 2010
Published by: Stockholm University Press
In partnership with: Paradigm Publishing Services

© 2010 Frank Sienz, Andrea Schneidereit, Richard Blender, Klaus Fraedrich, Frank Lunkeit, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.