Study of the development of the sea breeze and its micro-scale structure at a coastal site using a Multi-Tone Sodar system

Abstract

The purpose of this paper is to study the development of the coastal flow i.e. its micro-scale characteristics within the surface layer at the sea-land transition and to investigate the development of inland formation of cloudiness during merging of sea/land and valley- mountain breeze regimes. The area is the mountainous southern tip of Italy, about 50 km wide and 300 km long, in the Central Mediterranean Basin. Here, thermal meso-scale circulations and cloud formations on the mountains are pronounced because of their peculiar elongated shape. Upslope flow is very strong, due to the steepness of Apennines, and sea-breeze circulation is supported by the thermally forced meso-scale flows. Here, we present preliminary results from a case study during six consecutive days where sea/land breeze circulation was well developed and discuss the effect on the formation of inland clouds. Sea breeze days are selected by a sodar and surface meteorological station measurements. Cloud development is analyzed by subjective inspection of METEOSAT MSG images in the visible channel. The WRF (Weather Research and Forecasting) model is used to analyze the meteorological situation. The Institute of Atmospheric Sciences and Climate CNR-ISAC in house modular Multi-Tone Sodar system (PC-MTSodar) and the surface meteorological station are installed and operated at a coastal site located at about 300 m from the coastline. Preliminary results show that the methodology is viable to study the development of thermally forced meso-scale circulations over Calabria at micro and large scale and that these circulations can be intense over the peninsula thanks to its peculiar shape. It is shown that the formation of afternoon cumulus clouds, which may result in rainfall, is modulated by synoptic scale conditions. Further development will be a climatic assessment of the role of breezes on local climate.