Prediction model updating using the Rose-200 oblique ionospheric sounder at mid and higher latitudes

Differences between predicted and measured maximum usable frequency (MUF) values arise due to the short-term temporal variability of the ionosphere, particularly at high latitudes, and the inability of statistically based ionospheric models, used in HF prediction programs, to predict these variabilities. Techniques, however, are being investigated to improve ionospheric models by incorporating real-time ionospheric measurements, obtained using oblique or vertical incidence sounders. A technique, termed 'updating' (Uffelman et al. 1982, and Goodman and Daehler 1988) has been used with the MINIMUF prediction program at mid-latitudes to improve the predicted MUF. It has also been demonstrated by Uffelman et al. how the updating results obtained from a single path can be spatially extrapolated to improve MUF predictions on other spatially distributed mid-latitude paths. The present paper investigates the applicability of the updating technique to mid and higher-latitude propagation paths. Oblique soundings are recorded using ROSE-200 (Radio Oblique Sounding Equipment), and the MUF values measured over the mid and higher-latitude paths are compared with updated MUF predictions made using the APPLAB prediction model. The investigations are performed during a period of low auroral activity and approximately 48 hours of data are analysed with updates being performed at 6 hourly intervals.<>