Open Access

Auroral substorm dynamics and field line resonances

Earth, Planets and Space201454:BF03352440

https://doi.org/10.1186/BF03352440

Received: 24 April 2002

Accepted: 27 August 2002

Published: 21 June 2014

Abstract

Magnetospheric substorms frequently have oscillating auroral phenomena associated with them, and which may be related to field line resonances. In this paper we present an analysis of photometer data which displays such oscillations in luminosity. We use data from the Gillam station in the CANOPUS array for April 1, 2000. Clear pulsations in magnetometer and photometer data are observed at 2.2 mHz. The latitudinal distribution of the photometer pulsations indicates that the auroral luminosity variations, caused by precipitating electrons and protons, are modulated by large scale global compressional modes (field line resonances). The proton and electron auroras were found to oscillate essentially out of phase. As well, the variation of phase across the peak in the luminosity resonance follows the pattern expected for the coupling of resonant Alfve’n modes by normal compressional modes in the magnetotail.