A Three-Dimensional Numerical Model of the Sea Breezes Over South Florida

Abstract

An eight-level three-dimensional primitive equation model which includes a detailed boundary layer parameterization scheme has been used to describe the initiation and evolution of sea-breeze convergence patterns over south Florida as a function of the surface heat and momentum fluxes and of the large-scale synoptic forcing. A minimum grid spacing of 11 km was used. Model results are presented for several different initial conditions and the results, when compared against cumulus cloud and shower patterns, demonstrate that the dry sea-breeze circulations are the dominant control on the locations of thunderstorm complexes over south Florida on undisturbed days. It is also shown that, in contrast to the differential roughness, the differential heating between land and water over south Florida is the primary determinant of the magnitudes of convergence. The values of surface roughness, however, indirectly influence convergence patterns by affecting the intensity of the vertical turbulent transport of heat and momentum. It is found that the sea breeze over south Florida accumulates synoptic-scale moisture in the convergence zones, since the magnitudes of moisture convergence are relatively unaffected by evaporation from the ocean at least for a period of 10 hours or so. The results of the numerical experiments suggest that, in order to properly interpret the results of the Experimental Meteorology Laboratory's cloud-merger seeding experiments over south Florida, an appreciation and understanding of the sea-breeze circulations are required.