Large-Eddy Simulation of Internal Boundary Layers and Near-Surface Wind Estimation During Hurricane Landfalls

Accurate estimation of coastal near-surface winds during hurricane landfalls remains challenging, partly attributable to an insufficient understanding of the wind profiles within the internal boundary layer (IBL) induced by an abrupt surface roughness change. This study addresses this issue by performing three semi-idealized large-eddy simulations. Results indicate that a nascent log layer emerges within the IBL, and its depth gradually increases from ∼60 m near the coast to ∼400 m 12 km inland, where the boundary layer transition is nearly complete. This nascent log layer is superimposed by another log layer originating from the upstream marine boundary layer. While turbulence kinetic energy (TKE) is maximized near the surface over both water and land, peak TKE values over land are a factor of 2 greater due to the amplified near-surface vertical wind shear. The capability and uncertainty of coastal radars and radiosondes to detect IBL and estimate 10-m winds are discussed.