Evaluation and Improvement of a TKE-Based Eddy-Diffusivity Mass-Flux (EDMF) Planetary Boundary Layer Scheme in Hurricane Conditions

Abstract Accurately representing boundary layer turbulent processes in numerical models is critical to improve tropical cyclone forecasts. A new turbulence kinetic energy (TKE)-based moist eddy-diffusivity mass-flux (EDMF-TKE) planetary scheme has been implemented NOAA’s Hurricane Analysis and Forecast System (HAFS). This study evaluates EDMF-TKE hurricane conditions based on a recently developed framework using large-eddy simulation (LES). Single-column modeling tests indicate that produces much greater TKE values below 500-m height than LES benchmark runs different high-wind conditions. To these results, two parameters the were modified ensure match between PBL surface-layer parameterizations. Additional improvements made by reducing maximum allowable mixing length 40 m observations, adopting definition of height, nonlocal mass fluxes With modifications, profiles TKE, eddy viscosity, winds compare better with results. Three-dimensional idealized simulations an ensemble HAFS forecasts Michael (2018) consistently show tends produce stronger vortex smaller radius wind original EDMF-TKE, while gale-force unaffected. The code viscosity within compared code, which contributes inflow, especially annulus 1–3 times wind. shows promise forecast skill rapid intensification sheared environments.