IONOSPHERIC REFRACTION EFFECTS IN SLANT RANGE PROFILES OF AURORAL HF COHERENT ECHOES

The theory of auroral coherent echoes developed for VHF scattering by Uspensky et al. (1988, 1989) is applied to the interpretation of inten sity and Doppler velocity slant range profiles of HF radar aurora. The theoretical model includes the effects of irregularity aspect sensiti vity, ionospheric refraction of the radar beam, and the reception of s ignals from different heights. The predicted profiles of HF radar auro ra are compared with Schefferville HF radar observations in the freque ncy interval of 9-18 MHz. Satisfactory agreement is found between theo ry and experiment for the intensity profiles. However, there are signi ficant discrepancies for the Doppler velocity profiles. We discuss thi s lack of agreement in light of other recent observations.