资源环境科技发展态势分析平台

As a result of rapid changes in surface conditions when a landfalling hurricane moves from ocean to land, interactions between the hurricane and surface heat and moisture fluxes become essential components of its evolution and dissipation. With a research version of the Hurricane Weather Research and Forecasting Model (HWRF), this study examines the effects of the vertical eddy diffusivity in the boundary layer on the evolution of three landfalling hurricanes (Dennis, Katrina, and Rita in 2005).

Specifically, the parameterization scheme of eddy diffusivity for momentum K-m is adjusted with the modification of the mixed-layer velocity scale in HWRF for both stable and unstable conditions. Results show that the change in the K-m parameter leads to improved simulations of hurricane track, intensity, and quantitative precipitation against observations during and after landfall, compared to the simulations with the original K-m.

Further diagnosis shows that, compared to original K-m, the modified K-m produces stronger vertical mixing in the hurricane boundary layer over land, which tends to stabilize the hurricane boundary layer. Consequently, the simulated landfalling hurricanes attenuate effectively with the modified K-m, while they mostly inherit their characteristics over the ocean and decay inefficiently with the original K-m .