l557·7 nm Pulsations within Quiet Pre-breakup Aurorae at L = 8·7

Abstract

Pulsations in the [01] .A. 557�7 nm emission, with a typical period of 10-20 s, were consistently observed within quiet pre-breakup auroral forms from Mawson, Antarctica (L = 8'7), during 1967. By relating these observations to the modal location of the auroral oval, an indication of the parent magnetospheric region is gained. From these results, and other reports, it is concluded that optical pulsations are a basic feature of the auroral display. The occurrence of an 'optical auroral pulsation pearl necklace' is reported.