MULTISCALE NUMERICAL STUDY OF HURRICANE-ANDREW (1992) .1. EXPLICIT SIMULATION AND VERIFICATION

In this study, the inner-core structures of Hurricane Andrew (1992) ar e explicitly simulated using an improved version of the Penn State-NCA R nonhydrostatic, two-way interactive, movable, triply nested grid mes oscale model (MM5). A modified Betts-Miller cumulus parameterization s cheme and an explicit microphysics scheme were used simultaneously to simulate the evolution of the larger-scale flows over the coarser-mesh domains. The intense storm itself is explicitly resolved over the fin est-mesh domain using a grid size of 6 km and an explicit microphysics package containing prognostic equations for cloud water, ice, rainwat er, snow, and graupel. The model is initialized with the National Cent ers for Environmental Prediction analysis enhanced by a modified moist ure held. A model-generated tropical-storm-like vortex was also incorp orated. A 72-h integration was made, which covers the stages from the storm's initial deepening to a near-category 5 hurricane intensity and the landfall over Florida. As verified against various observations a nd the best analysis, the model captures reasonably well the evolution and inner-core structures of the storm. In particular, the model repr oduces the track, the explosive deepening rate (>1.5 hPa h(-1)), the m inimum surface pressure of 919 hPa preceding landfall, the strong surf ace wind (>65 m s(-1)) near the shoreline, as well as the ring of maxi mum winds, the eye, the eyewall, the spiral rainbands, and other cloud features. Of particular significance is that many simulated kinematic s, thermodynamics, and precipitation structures in the core regions co mpare favorably to previous observations of hurricanes. The results su ggest that it may be possible to predict reasonably the track, intensi ty, and inner-core structures of hurricanes from the tropical synoptic conditions if high grid resolution, realistic model physics, and prop er initial vortices (depth, size, and intensity) in relation to their larger-scale conditions (e.g., SST, moisture content, and vertical she ar in the lower troposphere) are incorporated.