12,000

We have over 12,000 students, from over 100 countries, within one of the safest campuses in the UK

93%

93% of Lancaster students go into work or further study within six months of graduating

Home > Research > Publications & Outputs > A superposed epoch analysis of auroral evolutio...
View graph of relations

Keywords

« Back

A superposed epoch analysis of auroral evolution during substorms: local time of onset region

Research output: Contribution to journalJournal article

Published

Article numberA00I04
Journal publication date14/10/2010
JournalJournal of Geophysical Research
Journal numberA5
Volume115
Number of pages9
Original languageEnglish

Abstract

Previous workers have shown that the magnetic local time (MLT) of substorm onset depends on the prevailing east-west component of the interplanetary magnetic field (IMF). To investigate the influence of the onset MLT on the subsequent auroral response we perform a superposed epoch analysis of the auroral evolution during approximately 2000 substorms using observations from the FUV instrument on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft. We subdivide the substorms by onset latitude and onset local time before determining average auroral images before and after substorm onset, for both electron and proton aurorae. We find that during the growth phase there is preexisting auroral emission in the MLT sector of the subsequent onset. After onset the auroral bulge expands eastward and westward, but remains centered on the onset sector. Approximately 30 min after onset, during the substorm recovery phase, the peaks in electron and proton auroral emission move into the postnoon and prenoon sectors, respectively, reflecting the “average” auroral precipitation patterns determined by previous studies. Superposed epoch analysis of the interplanetary magnetic field for the substorms under study suggests that the BY component of the IMF must be biased toward positive or negative values for up to a day prior to onset for the onset MLT to be influenced.

Bibliographic note

Copyright 2010 by the American Geophysical Union.