The seasonal characteristics of the breeze circulation at a coastal Mediterranean site in South Italy

摘要

We present a study on the characteristics of the sea breeze flow at acoastal site located in the centre of the Mediterranean basin at thesouthern tip of Italy. This study is finalized to add new data on breezecirculations over a narrow peninsula and present a unique experimentalcoastal site at about 600 m from the coastline in a flat open area at the foot ofa mountain chain located in a region of complex orography. We study theseasonal behaviour of the sea-land breeze circulation by analysing two yearsof hourly data of wind speed and direction, temperature, radiation andrelative humidity from a surface meteorological station, eighteen-monthsdata from a wind profiler, and two-year data from the ECMWF analysis.Results show that breezes dominate the local circulation and play a majorrole for the local climate. They are modulated by the season, through thesea-land temperature difference and the large-scale flow. The large-scaleforcing acts in phase with the diurnal breeze and opposes the nocturnalbreeze.In summer, the daytime difference between the land surface temperature and the SST (Sea Surface Temperature)reaches its maximum, while the nigh-time difference has its minimum. This causes a strong, frequent and intense diurnal breeze and a weak nocturnal breeze.In winter and fall the nocturnal difference between the sea and land surface temperature reaches amaximum value, while the diurnal difference is at its minimum value. This causes a strong, frequentand intense nocturnal breeze despite of the large-scale forcing that is usually opposed to local-scale flow.