SPACED ANTENNA AND INTERFEROMETRIC VELOCITY-MEASUREMENTS WITH MF AND VHF RADARS

The spaced antenna and interferometry techniques are applied to data c ollected on two MF radars (at Christchurch, New Zealand, and at Scott Base, in the Antarctic) and one VHF radar (the MU radar at Shigaraki, Japan). Velocity results obtained by the two techniques are compared a s functions of characteristics such as the temporal scale and anisotro py of the scatter. In general, there was good agreement between the tw o techniques; however, when the temporal scale is small (indicating tu rbulent scatter) there was less agreement. The interferometry techniqu e did not appear to be influenced greatly by anisotropy in the scatter . The interferometry technique was found to be affected by averaging o f the Doppler spectra and by the use of an extra receiver. It is sugge sted that less averaging of the spectra results in increased random no ise components in the spectra, which in the phase spectra are interpre ted as scattering from a greater range of zenith angles. It was found that the use of three receivers rather than four also lead to scatteri ng that appeared to originate from a greater range of zenith angles. T hese effects lead to lower interferometric velocity estimates that are more biased towards full correlation analysis (FCA) true velocities.