A NUMERICAL INVESTIGATION OF FLORIDA'S SEA BREEZE - CUMULONIMBUS INTERACTIONS (MESOSCALE METEOROLOGY, CONVECTIVE-ENVIRONMENTAL)

Florida's deep cumulus convective effects upon the mesoscale sea breeze environment are investigated using a numerical approach with supportive observational analyses. The mesoscale hydrostatic primitive equation model of Pielke (1974) is coupled with a modified convective parameterization from Fritsch and Chappell (1980), for investigating Florida's deep convective-environmental interactions.; Based on the three-dimensional simulations performed in this study, it is found that the convective-generated downdraft plays a crucial role in modulating the sea breeze environment as well as on subsequent convective developments. Three stages can be identified for the sea breeze-convective interrelationships. Stage 1 (sea breeze convergence stage) is associated with the establishment of coastal sea breeze convergence zones and embedded deep convection which vertically stretches the shallow solenoidal circulation (generated by dry sea breeze) to much deeper depths, thereby further enhancing the sea breeze convergence. Stage 2 (convective downdraft cooling stage) follows the onset of the relatively significant downdraft effects upon the penninsula-scale environment. The downdraft-induced surface cooling generates mesoscale pressure gradient forces near the surface surrounding the convective area. Together with the sea breeze surface flow, low-level convergence is generated on the upwind side which provides new favorable environments for initiating deep convection. A "four-cell" vertical circulation pattern is formed as a result of the upper tropospheric divergence, mid-tropospheric convergence and the surface divergence due to the downdraft cooling. Finally, Stage 3 (decaying stage) is associated with only mesoscale weaker upward and downward motions without new deep cumulus convective developments.; The model does not simulate properly the effect of Lake Okeechobee due to the use of 22 km as the horizontal grid spacing. On the other hand, the Florida deep convective-environmental interrelationship described above is found to be consistent with the observed behavior of deep convection along the west coast which is adequately resolved using the existing grid.