An investigation of the boundary layer dynamics of Sardinia Island under sea-breeze conditions

A numerical mesoscale model is used to study the wind field and the boundar y layer structure of the island of Sardinia during typical summer condition s. The numerical model is three-dimensional and employs a higher-order turb ulence closure scheme. The model simulations were performed for summer cond itions 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 pa tterns generally are dominated by topography, which leads to the developmen t 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 conver gence zones. Another interesting feature is the development of a cyclonic e ddy pattern during late-afternoon hours. The model results are compared wit h observations taken at a network of near-surface wind stations and rawinso nde profiles from the Cagliari airport. Available observations agreed relat ively well with model predictions.