VHF radar observations of anisotropic and isotropic scattering

Attention is paid to the contributions of Fresnel reflection, and anisotropic and isotropic turbulent scatter to signals at low VHF frequencies received at near vertical incidence from the troposphere and lower stratosphere. Use is made of observations carried out with the NERC MST radar facility located at Capel Dewi, some 3 miles from Aberystwyth. This operates at a frequency of 46.5 MHz with a peak power of 160 kW. Measurements are made with 8 μs pulses and 1 μs coding, providing returned power at 150 m height intervals. The analysis technique is concerned with the derivation of the three lowest moments of the spectrum of the returned echo to provide measures of the total returned power, the velocity in the radar beam direction, and the variance of this velocity within the radar volume, which indicates the intensity of turbulence