PC5 FIELD LINE RESONANCE FREQUENCIES AND STRUCTURE OBSERVED BY SUPERDARN AND CANOPUS

We have analyzed a number of low-m Pc5 field line resonance events obs erved simultaneously by one or more of the Super Dual Amoral Radar Net work (SuperDARN) radars and the Canadian Auroral Network for the OPEN Unified Study (CANOPUS) magnetometer array, At times there was excelle nt agreement in the Pc5 signal frequencies observed by radar and magne tometers, For events with good agreement in the measured signal freque ncies, there was also reasonable agreement in the observed resonance p ositions and m numbers. Sometimes, however, the ordering of frequencie s by their spectral power did not coincide between the radar and magne tometer data and even the frequencies of the spectral peaks did not al ways coincide. In these cases, there was also some apparent discrepanc y in the observed resonance positions and m numbers. The resonance hal f power widths observed by the magnetometers were found to be a factor of 2-6 wider than those measured with the radar, owing to the spatial integration by ground-based magnetometers of ionospheric current stru ctures having scale size less than ionospheric height. Although there was general agreement in the direction of the longitudinal propagation , the m numbers obtained from the magnetometer data were found to be s omewhat smaller that those calculated from the radar data. We consider and discuss possible reasons for the observed discrepancies.