Comparison of Planetary Boundary Layer Model Winds with Dropsonde Observations in Tropical Cyclones

Abstract

The values of surface winds simulated by the University of Washington (UW) two-layer similarity planetary boundary layer (PBL) model are compared with National Oceanic and Atmospheric Administration Hurricane Research Division global positioning system dropsonde observations and the surface wind analyses of a numerical weather prediction model. These three wind products compare fairly well at moderate wind speeds, away from the center of the storms where the coarse resolution of the numerical model is not a major factor. In the very high wind regime, the UW PBL model winds match the dropsonde observations fairly well, which is consistent with the unique characteristic of the PBL model being able to account for the nonlinear effects of organized large eddies. These eddies transport momentum and heat fluxes more efficiently than the smaller-scale, local turbulence can, leading to simulations of higher winds with mesoscale variability.