A statistical study of magnetic aspect effects associated with VHF auroral backscatter


  • J. A. Koehler,

  • G. J. Sofko,

  • V. Mehta


VHF auroral backscatter is usually assumed to show an aspect angle dependence on backscatter cross section of about −10 dB/deg. In the summer of 1981, an experiment was performed in northern Saskatchewan to measure, explicitly, this dependence at 50 MHz. The technique used was to simultaneously observe the same scattering volume from a number of receiving and transmitting locations. The data showed that the aspect sensitivity was highly variable and not obviously correlated with other geophysical phenomena. The spectral characteristics of the received backscatter showed a strong but also variable dependence on aspect angle. These observations, supported by some other previous experiments, suggest that there are important unexplained areas which cannot be accounted for by present theories of coherent backscatter.