HIGH PERFORMANCE VISUALIZATION CENTER INITIATIVE--CONVECTIVE INITIATION.

Marine and Atmospheric Sciences

HIGH PERFORMANCE VISUALIZATION CENTER INITIATIVE--CONVECTIVE INITIATION

Paul J. [Croft.sup.*], Duanjun Lu, Jan Hafner, Patrick J. Fitzpatrick, and R. Suseela Reddy, Jackson State University, Jackson, MS 39217

During the summer season, thunderstorms along the central gulf coast are often widespread and frequently occur in the absence of synoptic scale forcing. The sea breeze front is often a factor in the initiation of these storms. Twelve sea breeze cases during the summer in 1996 were selected based on the investigation of Medlin and Croft (1998). Two numerical modeling systems, the Navy's Coupled Ocean/Atmosphere mesoscale Prediction System (COAMPS) and the Pennsylvania State University-National Center for Atmospheric research (PSU-NCAR) fifth-generation Mesoscale Model (MM5), were employed to study the occurrence and structural evolution of sea breezes, and the interaction between sea breeze and base state flows. The two models were run for the same triple-nested domains centered over Mobile Bay, Alabama, with 49 x 49 grid points 927 km grid spacing), 43 x 43 grid points (9 km spacing), and 43 x 43 grid point (3 km spacing) for coarse, medium and fine meshes respectively. For summer base flows of easterly/southeasterly, northwesterly, or westerly/southwesterly wind, the sea breeze is developed before 1200 LST. The most unstable air is located close to or near the coast of the Bay first due to the strong temperature gradient zone that develops along the coastline. The rising areas move inland on both sides of the Bay as time goes on. The onshore flow tends to suppress the development of sea breeze circulation while offshore flow enhances the sea breeze. The physiographic features of the region also influence the sea breeze circulation.