Author(s): Panagiota Galiatsatou; Panayotis Prinos
Linked Author(s): Panagiota Galiatsatou, Panagiotis Prinos
Keywords: Storm surge extremes; Climate change; Non-stationary GEV
Abstract:
In the present work the effects of climate change on storm surge extremes in selected areas of the Greek Seas are studied. Storm surge data result from a two dimensional model of hydrodynamic circulation for the Greek Seas covering a period of 150 years (1950-2099) .The atmospheric forcing of the model comprises of wind and sea level pressure fields of the regional climate model Reg CM3. The available storm surge time series are separated in three parts of almost equal size, to represent the present, the short-term and the long-term future climate. Storm surge extremes of each period are first examined for possible trends in their frequency of occurrence and in their magnitude by means of a non-stationary GEV distribution function fitted to annual maxima. The analysis of the storm surge extremes then proceeds by using a nonstationary statistical GEV distribution function that simulates the variability within a year of the monthly maxima. The parameters of the distribution are modelled as harmonic functions of time representing the annual and the seasonal cycle. In each selected location and each period, twenty-six candidate models are fitted to the monthly maxima. To avoid overparameterisation and to select the appropriate number of parameters for each time period and each location, the Akaike Information Criterion with correction for small sample size and the deviance statistic criterion are utilized. After selecting an appropriate model for the extremes, time-dependent quantiles of storm surge within an one year period are assessed for each period and point considered. Apart from time dependent quantiles, annual return levels are also approximated by means of numerical integration of the fitted non-stationary model. The time dependent, as well as the annual quantiles for each point and for the three different periods (present and future climate) considered are compared to estimate the effects of climate change on storm surge extremes.
Year: 2015