Relation between optical emissions, particles, electric fields, and Alfvenwaves in a multiple rayed arc

Velocities of rays in auroral arcs were used to infer the perpendicular ele ctric fields above the acceleration region. Using rocket measurements of el ectron energy as a proxy for the high-altitude potential, the high-altitude perpendicular electric fields were calculated and found to be in good agre ement with those derived from the ray motions. Additionally, a 0.6 Hz oscil lating electric field at high altitude was postulated on the basis of the p assing rays. Such a field was also calculated from the electron energy meas urements and was found to be closely related to an Alfven wave measured on the payload following a delay of 0.8 s. The measured electron energy flux a greed well with the auroral luminosity down to scale sizes of about 10 km. The combination of ground-based imaging acid the measured energy flux also allowed a determination of the lower border altitude of the arcs. They were found to be somewhat higher (130 km) than expected on the basis of the ele ctron energy. A tall rayed are with a lower border height of 170 km was ass ociated with a burst of suprathermal electrons on the poleward edge of the aurora.