The eosphere/ring current interface: IMAGE observations of ENAs emitted from low altitude
Abstract
The Medium (MENA) and High (HENA) Energy Neutral Atom imagers on NASA's IMAGE satellite have been observing ring current ENA emissions since the IMAGE launch. These emissions have often contained a component emitted from very low altitude. This component has often appeared to be highly localized and, at times, very bright when observed from high altitude along the IMAGE orbit, though the apparent localization is at least partly due to highly non-isotropic (beaming) emission. Recently, the IMAGE orbit line of apsides has precessed through low geomagnetic latitudes, offering views of low altitude ENA emission regions from relatively low altitude and high latitude, often sequentially from over the northern and southern poles. From these vantage points we observe low altitude ENA emissions that are in fact strongly peaked in pitch angle at the emission point and also strongly peaked in Invariant Latitude distribution. The MLT distributions show a deep minimum on the day side for the cases studied to date. We will present these observations, compare them with current thinking on the dynamical interaction at the exosphere/ring current interface, and comment on the geophysical significance of these observations.
- Publication:
-
35th COSPAR Scientific Assembly
- Pub Date:
- 2004
- Bibcode:
- 2004cosp...35.3887P