Magnetic local time extent of ion outflow during substorm recovery

Abstract

Ions from the Earth's ionosphere are an important component of the coupled magnetosphere-ionosphere system. These ions are accelerated out of the ionosphere in the auroral zone. As they gain altitude, a fraction of them are charge exchanged, producing energetic neutrals. These neutrals (in the energy range from ∼10 to ∼300 eV) are imaged by the Low Energy Neutral Atom (LENA) imager on the Imager for Magnetopause to Aurora Global Exploration spacecraft. From these images, the instantaneous local time extent of the ion outflow is determined. These data show that, during times of substorm recovery, the local time extent of the outflow is large and variable, typically centered on the dayside, but often extending over nearly the entire auroral oval. The local time extent appears to encompass the ionospheric footprint of the cusp. Copyright 2008 by the American Geophysical Union.