Description
This work examines the structure of turbulence in a large eddy simulation (LES) of the hurricane rapid intensification (RI) process, which is driven by convective bursts occurring within the inner core of the system. The simulation was conducted at 60-meter grid spacing with a high-order continuous Galerkin (spectral element) dynamic core coupled to observational latent heating estimates from a real RI case. The model data allows for an assessment of the boundary layer turbulence relative to typical planetary boundary layer (PBL) parameterization schemes. For example, we analyze a typical PBL height, defined as the height where the inflow reaches 10% of the maximum inflow in the lower levels, relative to the structure of turbulence kinetic energy (TKE) in the core. In several regions, consecutive columns of TKE maxima extend well above the typical PBL height, suggesting these standard metrics may need to be revised. Moreover, further analysis suggests these vertically-stretched TKE formations are primarily induced by vertical perturbation winds tied into thin spiral bands moving around the vortex. In an attempt to characterize these spiral bands, comparisons were made with observational data from the Imaging Wind and Rain Airborne Profiler (IWRAP) radar system. Spectral analysis between the two datasets reveals similar wavelength scales for the spiral bands. Behavior of computed eddy momentum flux quantities near the eyewall hints the possibility of the TKE maxima being convectively driven, but more spatial analysis is necessary for confirmation. As the research progresses, findings from the idealized model will continue to be compared with real observations, primarily IWRAP data. The overall results of this project will help improve the forecasting of the hurricane RI process, which can protect lives and property across the world.