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ABSTRACT
The Mediterranean has been identified as one of the most responsive regions to climate change. It has been conjectured that one of the effects of a warmer climate could be to make the Mediterranean Sea prone to the formation of hurricanes. Already in the present climate regime, however, a few of the numerous low pressure systems that form in the area develop a dynamical evolution similar to the one of tropical cyclones. Even if their spatial extent is generally smaller and the life cycle shorter compared to tropical cyclones, such storms produce severe damage on the highly populated coastal areas surrounding the Mediterranean Sea. This study, based on the analysis of individual realistically simulated storms in homogeneous long-term and high-resolution data from multiple climate change scenarios, shows that the projected effect of climate change on Mediterranean tropical-like cyclones is decreased frequency and a tendency toward a moderate increase of intensity.
1. Introduction
It is known since the early times of meteorology (Meteorological Office 1937) that the Mediterranean Sea, because of its peculiar features, such as the interplay of the complex topography and orography and the geographical location between the subtropics and midlatitudes, is characterized by the formation of a large number of low pressure systems (Trigo and Davies 1999), mostly baroclinic in nature (Trigo et al. 2002). It has been suggested that the increased sea surface temperature in an anthropogenically warmed climate could lead to favorable conditions for the formation of hurricanes in the Mediterranean Sea (Gaertner et al. 2007). After the advent of satellite meteorology in the last decades of the twentieth century, on the other hand, evidence emerged (Ernst and Matson 1983; Rasmussen and Zick 1987) indicating that a few mesoscale vortices showing a striking resemblance to tropical latitude hurricanes occasionally do occur over the Mediterranean Sea. Such storms exhibit a cloud structure characterized by a central eye surrounded by spiral-shaped cloud bands, and the strong winds associated can reach hurricane strength; the most intense storms of this kind have thus been termed Mediterranean hurricanes (medicanes). The limited available observations of the atmospheric fields around medicanes (Pytharoulis et al. 2000; Reale and Atlas 2001; Moscatello et al. 2008; Lagouvardos et al. 1999) showed further similarities between their dynamical features and the...