Numerical Simulations of Hurricane Floyd (1999)


Hurricane Track and Rainfall


MM5 Configuration:

The research group at RSMAS/University Miami (with the lead PI - Dr. Shuyi Chen) has developed a vortex-following, nested-grids version of the fifth generation PSU/NCAR nonhydrostatic atmospheric mesoscale model (MM5) for hurricane research and modeling. In this study, we initialize the MM5 at 0000 UTC on Sept. 11, 1999 and integrate the model to 0000 UTC on Sept. 17, 1999. Initial and lateral boundary conditions for MM5 are derived from NCEP global model initial fields. Sea-surface temperatures are from NCEP global SST analysis. The MM5 simulation employs 4 nested-grid levels. We have modified the MM5 so that the fine meshes follow the vortex center (as determined by the location of the local minimum in the 500 hPa geopotential height field). The coarsest mesh grid spacing is 45 km in the horizontal, and the finer meshes have grid spacings of 15 km, 5km, and 1.67 km. There are 28 levels in the vertical, from the surface to 50 mb. The vertical grid spacing is variable, with the highest resolution in the boundary layer.


Simulated and Actual Tracks

Simulated Rainfall Animation




Inner-core Rainfall Animation




Sensitivity to Model Grid Resolution



Surface Rain Rate (15 km)

Surface Rain Rate (1.67 km)



Surface Heat Flux (15 km)

Surface Heat Flux (1.67 km)



Hurricane Induced Ocean Surface Waves

WAVEWATCH III Configuration:

The ocean surface wave model used in this study is the NOAA WAVEWATCH III. The grid spacing of the ocean-wave model is 1/6 degree (~16 km). The wave spectrum is discretized into 25 frequency bands and 48 directional bands. The surface winds from the MM5 simulations are interpolated onto the WAVEWATCH III grid and used in the source term of the equation governing the evolution of the wave action density spectrum. Currently the MM5 and WAVEWATCH III are run in a fully coupled mode.

Simulated S. Wave Height Animation

Simulated Wavelength Animation



Hurricane Intensity Simulated by the Coupled MM5-WAVEWATCH III Model


Maximum Surface Wind Speed