Long-Term Global Distributions of Mesoscale Variations in Atmospheric Radio Refraction Obtained from the GPS Champ Satellite Data

Abstract

We obtain average global distributions of the variances of the mesoscale variations in the atmospheric radio-refraction index (refractive index) at altitudes of 5–35 km from the data of the radio-occultation experiments performed during operation of the low-orbit GPS CHAMP satellite in the period 2001–2009. The filtering of the vertical profiles of the radio-refraction index allows one to determine the variances of the variations with vertical scales below 8 km. The latitudinal-temporal distributions of the zonal-mean variances of the index demonstrate significant interannual variations at various altitudes. Seasonal variations in the variances of radio refraction are studied. Quasi-biennial oscillations at low latitudes are revealed. Acoustic-gravity waves and turbulent and convective motions in the atmosphere can cause a spread of the radio-refraction index.