AN EMPIRICAL MODEL OF THE EFFECTS OF IONOSPHERIC ELECTRON DENSITY VARIATIONS ON HF RADAR PROCESSING

The High Frequency hybrid radar mode combines sky and surface wave propagation. As all High Frequency radars, it can be impacted by ionospheric instabilities. A behavioral model able to include ionospheric spatial and temporal variations has been implemented to estimate the impact of ionospheric irregularities on radar signal processing and Doppler-distance images. In this work, probabilistic models of the ionospheric fluctuations in the ray tracing have been introduced using the phase path fluctuation only. Based on Shkarofsky’s spectral power density, random variations on some parameters of Booker’s electron density profile have been performed to generate disturbed electron density profiles. Afterwards, a propagation delay, integrated in the received radar signal, has been calculated in terms of phase path variation. Moreover, the temporal aspect of the ionospheric variations has been macroscopically implemented by a filtering step according to the Total Electron Content variation. Results of this simulation are presented with the corresponding statistics. Doppler and distance distributions have been computed for several filter cut-off frequency values and for different Shkarofsky’s spectral power density parameters. At last, the process described above works properly: its results have been successfully compared with actual radar data for this purpose.