TitleFar-ultraviolet signature of polar cusp during southward IMF Bz observed by TIMED/Global Ultraviolet Imager and DMSP
Publication TypeJournal Article
Year of Publication2005
AuthorsZhang, Y, Meng, C-I, Paxton, LJ, Morrison, D, Wolven, B, Kil, H, Newell, P, Wing, S, Christensen, AB
JournalJournal of Geophysical Research: Space Physics (1978–2012)
Volume110
Keywordscusp aurora
Abstract

The coincident TIMED/Global Ultraviolet Imager (TIMED/GUVI) optical and DMSP particle observations have revealed new features of the optical signature of the polar cusp under a southward interplanetary magnetic field (IMF). We have found that cusp auroras usually take the shape of a thin arc with a width around 100–200 km. This provides the first far-ultraviolet evidence of the narrow cusp under a southward IMF [Newell and Meng, 1987]. The cusp auroras could extend down to 0800 magnetic local time (MLT) in the morningside and 1400 MLT in the duskside. Its length is about a few thousand kilometers. A large solar wind density, speed, and IMF are necessary conditions for GUVI to observe the cusp aurora. We found that the cusp location at 1200 MLT changes linearly (−10 nT Bz < 0 nT) and nonlinearly (Bz < −10 nT) with the IMF Bz. The nonlinear effect can be explained by an L−3 dependence of the Earth's equatorial magnetic field.

DOI10.1029/2004JA010707


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