Spectral characteristics of turbulence in the hurricane boundary layer over the ocean between the outer rain bands

Abstract

Spectra and cospectra of wind velocity, potential temperature and humidity have been analysed using data collected in the atmospheric boundary layer in Hurricanes Fabian (2003) and Isabel (2003) during the Coupled Boundary Layer Air– Sea Transfer (CBLAST)—Hurricane experiment. The spectra and cospectra are normalized following the surface layer scaling methods according to similarity theory. It is found that the CBLAST data gathered in the mixed layer between the outer rain bands below 400 m can be grouped into well-defined curves for spectra of wind velocity, potential temperature and humidity, and for cospectra of momentum and humidity flux. However, the cospectra of sensible heat flux do not exhibit well-defined universal shape. The CBLAST universal shape spectra and cospectra generally resemble the shapes of those from previous studies, but shift to higher frequencies that correspond to smaller wavelengths of turbulent eddies that contain most of the energy. This work highlights the structural difference between the hurricane boundary layer and the standard atmospheric boundary layer over land and ocean. Copyright © 2010 Royal Meteorological Society