AN ALTERNATIVE LOOK AT THE ASPECT SENSITIVITY OF AURORAL RADAR BACKSCATTER - A FORWARD SCATTER EFFECT

A simple model for diffuse forward scatter is presented in order to ac count for the aspect angle dependence of auroral radar backscatter ove r a wide range of aspect angles as can be observed by UHF radars. The basic assumption is that the backscatter itself is highly anisotropic but that the incident rays are partially scattered by quasi-isotropic small to medium scale irregularities in the bottom/top part of the E/D regions. The model is developed to provide a theoretical forward scat ter/aspect angle relationship, which is compared with the observations . The model exhibits reasonable agreement with recent 440-MHz Millston e Hill radar observations over aspect angles ranging between 0 and 10 deg. Other supporting evidence is also presented.