An Investigation of the Boundary Layer Dynamics of Sardinia Island under Sea-Breeze Conditions

Abstract

A numerical mesoscale model is used to study the wind field and the boundary layer structure of the island of Sardinia during typical summer conditions. The numerical model is three-dimensional and employs a higher-order turbulence closure scheme. The model simulations were performed for summer conditions characterized by weak synoptic forcing from the northwest and clear skies. These conditions favor the development of thermal circulations, the most significant of which are the sea-breeze systems. The nighttime wind patterns generally are dominated by topography, which leads to the development of strong drainage flow. On the other hand, as revealed in the simulated wind field, at midday the wind has an onshore component at virtually every coastline. The well-organized sea-breeze systems interact to produce convergence zones. Another interesting feature is the development of a cyclonic eddy pattern during late-afternoon hours. The model results are compared with observations taken at a network of near-surface wind stations and rawinsonde profiles from the Cagliari airport. Available observations agreed relatively well with model predictions.