Satellite and Radar Analysis of Mesoscale Features in the Tropics.

Tropical convection in the Florida, Cuba and upper Bahamas areas are studied using once-daily ESSA 5 and 7 satellite cloud mosaics during the period 14 June to 22 October 1968. The approach utilizes cloud cover information which are tabulated for each element of a 20 x 20 grid array and processed using the computer. It is found that the average coverage over Florida is 38 percent, over Cuba is 38 percent, and over the open water is 24 percent. Daily anomalies of cloudiness are discussed. Computations show that the cloud cover over South Florida correlates quite well with rain data and with humidity between 700 and 500 mb, but poorly with low-level divergence and vorticity. Other types of correlations are made and maps are presented showing the correlation coefficients of cloudiness on a square-by-square basis with rain data in South Florida during various wind regimes at 850 mb. The satellite data are then stratified into five convective activity regimes which are determined on the basis of the number of stations receiving rain during the day. It is shown that the rainfall and cloud cover are characteristically different in each regime. Maps are presented showing typical cloud cover during and preceding each type of activity regime. Rainfall analysis covering the entire period reveals that the sea-breeze regime was quite active. Author