Turbulence and Coherent Structure in the Atmospheric Boundary Layer near the Eyewall of Hurricane Hugo (1989)

In this talk we present an analysis of observational data collected from NOAA'S WP-3D research aircraft during the eyewall penetration of category five Hurricane Hugo (1989). The 1 Hz flight level data near 450m above the sea surface comprising wind velocity, temperature, pressure and relative humidity are used to estimate the turbulence intensity and fluxes. In the turbulent flux calculation, the universal shape spectra and co-spectra derived using the 40 Hz data collected during the Coupled Boundary Layer Air-sea Transfer (CBLAST) Hurricane experiment are applied to correct the high frequency part of the data collected in Hurricane Hugo. Since the stationarity assumption required for standard eddy correlations is not always satisfied, different methods are summarized for computing the turbulence parameters. In addition, a wavelet analysis is conducted to investigate the time and special scales of roll vortices or coherent structures that are believed important elements of the eye/eyewall mixing processes that support intense storms.