An improved knowledge of the Mediterranean hydrological cycle and its variability is needed which requires a better understanding of the mesoscale atmospheric flows like sea-breezes, which transport moisture over fairly large distances. 2006).īreeze phenomenon has never been investigated in global climate models (GCMs), since they have generally been used with too coarse horizontal grid resolution to explicitly resolve breeze circulation (i.e.>100 km). 2006) or by major urban areas (Lemonsu et al. 2005a, b) or by synoptic wind (Estoque 1962 Arritt 1993), and particularly by Mistral (Bastin et al. The inland penetration which controls inland moisture advection and often determines the band where convection is triggered during warm seasons, can be modulated by interaction with mountain slopes (Kusuda and Alpert 1983 Bastin and Drobinski 2005), channeling in local valleys (Bastin et al. The horizontal extent of the breeze circulation is expected to be even larger in the Southern shore of the Mediterranean region as it scales as the Rossby deformation radius, which is inversely proportional to the Coriolis parameter (Rotunno 1983 Dalu and Pielke 1989 Drobinski and Dubos 2009 Drobinski et al. 2006) and play an important role in inland transport of moisture (Bastin et al. Such differential heating produces breeze systems which can extend over a horizontal range of 100–150 km inland (Drobinski et al. During daytime (nighttime), land temperature exceeds (is lower than) the sea surface temperature. During this period, surface heating produces a significant thermal difference between land and sea. In the Mediterranean region, sunny weather occurs over a rather long period of the year, from spring to fall. The Mediterranean Sea acts as a major source of atmospheric moisture for the atmosphere in the region which controls offshore (Luca et al. 2001), which are companion winds blowing south from the French Mediterranean coast to the African coasts (Salameh et al. 1999), topographically-induced strong winds like Mistral (e.g. The morphological complexity of the basin leads to the formation of intense weather phenomena, such as intense cyclogenesis (e.g. 1), plays a crucial role in steering airflow. Indeed, the complex geography of the region, which features a nearly enclosed sea with high sea surface temperature (SST) during summer and fall, surrounded by very urbanized littorals and mountains (Fig. 1982) and a large variability at mesoscale. Located between the midlatitude storm rainband and the Sahara Desert, the Mediterranean region experiences a profound seasonal hydrological cycle, with wet-cold winters and dry-warm summers (Peixoto et al. The Mediterranean basin has quite a unique character that results from both physiographic and climatic conditions and historical and societal developments. The inland limit of significance is imposed by the vertical dilution in a deeper continental boundary-layer. The temperature anomalies are quickly damped by strong surface heating over land, whereas the water vapor mixing ratio anomalies are transported further inland. However, the SST anomalies are not of sufficient magnitude to affect the large-scale sea-breeze circulation. Temperature and moisture anomalies are created in direct response to the SST anomaly and are advected by the sea breeze over land. The coupled simulation provides a more realistic representation of the evolution of the SST field at fine scale than the atmosphere-only one. One result of this study is that these simulations reproduce remarkably well the intensity, direction and inland penetration of the sea breeze and even the existence of the shallow sea breeze despite the overestimate of temperature over land in both simulations. In order to explicitly represent the two-way interactions at the atmosphere-ocean interface in the Mediterranean region and quantify the role of air-sea feedbacks on regional meteorology and climate, simulations at 20 km resolution performed with WRF regional climate model (RCM) and MORCE atmosphere-ocean regional climate model (AORCM) coupling WRF and NEMO-MED12 in the frame of HyMeX/MED-CORDEX are compared. Sea breezes play an important role in inland transport of moisture especially between late spring and early fall.

In the Mediterranean basin, moisture transport can occur over large distance from remote regions by the synoptic circulation or more locally by sea breezes, driven by land-sea thermal contrast.

Sea breeze wind