Sensitivity of Hurricane Charley simulations to changes in the WRF model

Numerical simulations were performed with the Weather Research and Forecast Model (WRF) version 2.0 to study the impact of cloud microphysics and cumulus parameterization on the track, intensity and precipitation distribution of Hurricane Charley (2004).

The WRF was run with variable horizontal resolutions of 10 and 25 km with a forecast length of 24 hours, from 12 UTC August 13 to 12 UTC August 14, which encompassed Charley's landfall on the central Gulf Coast of Florida. Three varying cloud microphysics schemes were coupled with two varying cumulus parameterizations to yield a total of six configurations per horizontal resolution and time step.

Results from the sensitivity simulations show that 1) tropical cyclone intensity and precipitation features are largely responsive to changes in the cumulus parameterization, 2) the use of smaller computational time steps at coarser resolution results in a weaker cyclone intensity and that this may be explained by latent heat release from the respective explicit moisture schemes, 3)there is a strong sensitivity of precipitation to the horizontal resolution and the 10 km runs capture the banding structure of the precipitation that the 25 km runs fail to resolve, and 4) the explicit moisture scheme makes a more significant contribution to precipitation amounts over land, which may partially accounted for in examining the details of the land-surface model employed by the WRF.

The results of this study have implications for the mesoscale modeling of land-falling tropical cyclones, specifically in the resolving the intensity and distribution of precipitation. Recommendations for WRF configurations in modeling land-falling tropical cyclones at various horizontal resolutions are offered along with suggestions for further research, especially involving modifications to the explicit and implicit moisture schemes.