Spectral Properties of Turbulence and the Structure of the Atmospheric Boundary Layer

Abstract

A discussion of the spectral and cross-spectral properties of eddies in the nocturnal boundary layer is presented. The dependence of the spectra on the vertical structure of the boundary layer is studied. Meteorological data collected by the British Antarctic Survey during the austral winter of 1986 at Halley station, Antarctica are used to obtain profiles of wind, temperature and the local Richardson number (Ri) up to 40m. Cross-spectral analysis is used to determine whether the nature of the observed eddies is primarily turbulent of whether their structure is characteristic of coherent internal gravity waves. It is found that the cross-spectral phases indicate the presence of turbulent eddies only in regions where Ri is less than the critical value of 1/4.