Estimating The Effects Of Climate Change On Storm Surge Extremes In The Greek Seas

Panayota Galiatsatou

Chair(s): dr. Makropoulos

Tuesday 30 june 2015

17:00 - 17:15h at Central America (level 0)

Themes: (T) Special session, (ST) Coasts at threat in Europe

Parallel session: 7H. Special session: Coasts at threat in Europe

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 (1951-2100). The atmospheric forcing of the model comprises of wind (wind speed and wind direction) and sea level pressure fields of the regional climate model RegCM3. The analysis of the storm surge data is performed by means of a non-stationary 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. The available storm surge time series are separated in three parts of equal size (fifty years each), in order to represent the fifty years of the current, the short-term and the long-term future climate. 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 is 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.