Near-Earth Substorm Onset - A Coordinated Study

MAL PERSSON*, HJ OPGENOORTH, T.I. Pulkkinen, AI ERIKSSON, PO DOVNER, GD REEVES, RD BELIAN, M ANDRE, LG BLOMBERG, RE ERLANDSON, MH BOEHM, AT AIKIO, I. Häggström

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

We present simultaneous satellite and ground-based measurements of a substorm. Throughout the initial substorm expansion, southward drifting arcs are observed poleward of the expanding substorm aurora, indicating two independent systems of particle precipitation. Freja passes the brightening onset arc in the topside ionosphere near the moment of the substorm onset, observing an Alfven wave, field aligned current and oxygen ion outflow. The substorm onset occurs at low magnetospheric L-shells, near the poleward edge of the region of trapped particles. The location and time for the substorm injection are confirmed by geostationary spacecraft together with magnetometers, all-sky cameras and radar on the ground. We believe that the substorm onset may be triggered by modification of the oxygen content of the inner magnetosphere during the growth-phase caused by ionospheric ion outflow.

Original languageEnglish
Pages (from-to)1875-1878
Number of pages4
JournalGeophysical Research Letters
Volume21
Issue number17
DOIs
Publication statusPublished - 15 Aug 1994
MoE publication typeA1 Journal article-refereed

Cite this

PERSSON, MAL., OPGENOORTH, HJ., Pulkkinen, T. I., ERIKSSON, AI., DOVNER, PO., REEVES, GD., ... Häggström, I. (1994). Near-Earth Substorm Onset - A Coordinated Study. Geophysical Research Letters, 21(17), 1875-1878. https://doi.org/10.1029/94GL01426