Numerical modeling of storm surges in the Mediterranean Sea under climate change

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Christos Makris, Yannis Androulidakis, Yannis Krestenitis, Katerina Kombiadou, Vassilis Baltikas

Chair(s): dr. Vojinovic

Tuesday 30 june 2015

15:05 - 15:20h at Mississippi (level 1), Central America (level 0)

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

Parallel session: 6H. Special session: Coasts at threat in Europe

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Extreme storm surge events pose a great threat to low-elevation coastal areas and can cause loss of land and property, damages to structures, and human casualties. Hereby, we explore the trends of meteorologically induced extremes of sea level in the Mediterranean for a period of 150 years (1951-2100), under IPCC’s A1B climate scenario that considers increasing future concentrations of atmospheric greenhouse gases. In this framework, we use a high spatial resolution model of 2-D shallow water equations for the hydrodynamic simulation of storm surges, namely the Mediterranean Climate Surge Model (MeCSM). In situ measurements from several areas, during the last 50 years, are used to evaluate both the atmospheric climate forcing and MeCSM results. Statistical measures (Storm Surge Index, high-order percentiles, conditional probabilities etc) and spatial distribution of extremes show good agreement between historical data and simulations. This confirms MeCSM’s ability to estimate the sea-surface response to future climatic conditions. We also investigate the future trends, the variability and occurrence frequency of local extremes and the main forcing mechanisms that can induce strong surges in the Mediterranean basin. Our results support that there is a general decreasing trend in storminess under the considered climate scenario. However, this is mostly related to the occurrence frequency of sea-surface maxima, the duration and the spatial coverage of the storm surges, yet not to the actual magnitudes of sea level maxima that can increase during the 21st century. We show that the different morphological characteristics of the regional Seas in the Mediterranean basin have a significant influence on the variability of sea-surface maxima. There are also clear distinctions in the contributions of winds and pressure fields to the sea level height for various regions of the Mediterranean, as well as on the seasonal variability of extremes under the A1B scenario; e.g. peak surges are predicted to be mainly induced by low-pressure systems and favorable winds in the Northern Aegean and the Adriatic, respectively. This research is part of the THALES Program under the Project CCSEAWAVS (www.thalis-ccseawavs.web.auth.gr), which aims on estimating the effects of Climate Change on sea level and wave climate of the Greek seas.