Implications of meteor observations by the MU radar

We report high resolution meteor echo observations using the Kyoto University Middle and Upper (MU) Atmosphere 46.5 MHz Radar When the MU radar was pointed perpendicular to the geomagnetic field lines (B), numerous long-lived range spread trail echoes were observed which were largely absent when the beam was pointed in the vertical and parallel-to-B directions. This shows that this type of trail echo is largely due to scattering structures aligned along B. Additionally, nearly all the head echoes displaying an along-the-beam velocity component were followed by range spread echoes in the perpendicular-to-B pointing geometry. This demonstrates that meteoric field aligned irregularity is present in essentially all meteors up to the detection limit of the MU radar Practically all the spectra are limited within a bandwidth corresponding to a Doppler shift of 320 m/s, suggesting that the two stream instability is absent most of the time. Meteoric field aligned structures can be a potential error source for aeronomical applications if they are not appropriately considered.