Remote sensing of high-latitude ionization with the ISIS 2 auroral scanning photometer


  • Richard R. Vondrak,

  • John S. Murphree,

  • C. D. Anger


Kilovolt electron precipitation is the primary source of ionization in the high-latitude nighttime E region. Space-based measurement, or inference, of the energy distribution of these electrons can be used to specify the distribution of high-latitude ionization. In certain cases, remote sensing by imaging of auroral luminosities at two appropriate wavelengths can be used to infer both the electron energy flux and the electron energy distribution. To validate the capabilities of deriving ionospheric parameters from such observations, we have compared simultaneous measurements by the Chatanika radar and the ISIS 2 auroral scanning photometer which measures the spatial distribution of auroral emissions at 557.7 nm and 391.4 nm. The ISIS 2 images included a variety of high-latitude phenomena, such as auroral bands and a detached arc in the evening sector trough. Spatial enhancements in the auroral luminosities were associated with regions of increased E region ionization, provided the luminosities were corrected for earth albedo effects. Quantitative comparisons of the radar measurements and the ionization profiles inferred from the satellite data demonstrate the capabilities of the satellite-based remote sensing technique.