Study of a Sea-Breeze Case through Momentum, Temperature, and Turbulence Budgets

A simulation with the Meso-NH model over the island of Mallorca, Spain, has been made in a case of synoptic high pressure (5 June 2010) that allowed the development of sea breezes (SB) in the three main basins of the island. The results compare well to the available observations and are qualitatively very close to a previous idealized study with no synoptic forcing made by Ramis and Romero in 1995. The temporal and spatial structure of the SB in the southeastern basin is analyzed with the use of the momentum, temperature, and turbulence kinetic energy budgets provided by the numerical model. Five stages of evolution from before dawn to after sunset are discussed, identifying the main physical mechanisms at play. The morning land heating warms the land and the air over it until an air temperature gradient is created and a marine flow accelerates inland, dragged by turbulence in the low layers. The upper part of the inland current and the layers just above are dominated by compensatory motions, which oppose the corresponding pressure gradient at these levels. These mechanisms last while the SB is active, with significant effects from the local topography, and they decrease in intensity as sunset approaches. This relatively simple case has been used to check the goodness of two analytical models of the SB that perform relatively well because they use turbulence as a surrogate for the missing advection terms in the layers above 200 m. These models are formulated here in a more consistent manner in the turbulence parameterization than were the original propositions.