LONG-TERM GOALS

Our recent studies have found that hurricane boundary layer turbulences, which can only be parameterized in the current weather-prediction models, play significant roles in controlling the hurricane intensity. The long-term goal of this project is thus to improve the hurricane intensity forecast by developing a more physically based turbulence parameterization scheme. OBJECTIVES The turbulence effect on the hurricane intensity can be quantified only if the turbulences can be resolved in the numerical models. One objective of the current project is to perform a set of large-eddy simulations with increasing resolution until the statistics are converged. These simulations will then be analyzed to estimate eddy-diffusion coefficients for use in weather-prediction models. APPROACH AND WORK PLAN Because of the multi-scale nature of hurricanes, the proposed large-eddy simulation work is also a challenging computational problem. A three-dimensional research cloud model (CM1) with horizontal grid stretching capability is used to conduct convergence test. The Weather Research and Forecasting (WRF) model is used as a weather-prediction model to examine the eddy-diffusion coefficients obtained from CM1 simulation in both idealized and real-data hurricane cases