A Climatology of Atmospheric Wavenumber Spectra of Wind and Temperature Observed by Commercial Aircraft

Abstract

Atmospheric wavenumber spectra of wind and temperature have been obtained from over 6000 commercial aircraft flights made during the Global Atmospheric Sampling Program. Temperature and velocity spectra are approximately the same shape over the range of wavelengths 2.6 to 104 km. Spectral slopes are close to −5/3 in the range 2.6 to 300–400 km and are independent of latitude, season and location in the troposphere or stratosphere. At larger scales, spectral slopes steepen considerably and approach −3. It is found that spectral amplitudes of wind and temperature have log-normal frequency distributions Spectral amplitudes in the range 2.6 to 400 km vary somewhat with latitude, season and location in the troposphere or stratosphere. Temperature spectral magnitude varies more than velocity spectral magnitude, and is largest in the stratosphere and winter troposphere and smallest in the tropical troposphere. Meridional velocity spectral amplitude varies only slightly from the troposphere to the stratosphere but doe show a significant variation with latitude being smallest in the tropics. Zonal velocity spectral amplitude varies with latitude considerably less than the meridional velocity spectral amplitude. The seasonal variation of spectral amplitude is about the same at meridional for meridional and zonal velocities, with smallest values observed during summer.