Combined EISCAT and All‐Sky Camera observations of auroral structures

Abstract

Discrete arc structures were identified from EISCAT data on March 11, 1984 which were simultaneously recorded on All‐Sky camera pictures from the Kilpisjärvi station in Finland. From the electric field measurements supplied by the tri‐static UHF facility, some privileged orientation has been found through the requirement of a uniform tangential electric field across the arc structure, which corresponds to the preferential arc alignment as deduced from camera pictures. Additional fold structures, resolved by the All‐Sky camera, develop along the preexisting arcs which still organize the electric field fluctuations in their vicinity.