Conjugate observations of ENA signals in the high-altitude cusp and proton auroral spot in the low-altitude cusp with IMAGE spacecraft

Abstract

On 28 April 2001, significant enhancements of neutral atom signals were detected in the direction of a high-altitude cusp by the Low-Energy Neutral Atom (LENA) imager onboard the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE). Simultaneously, proton auroral emission was observed in the low-altitude cusp by the Far-Ultraviolet Instrument (FUV) on the IMAGE spacecraft. The temporal variations of their intensities showed a good correlation, suggesting they had a common source. During a brief period, the proton auroral spot moved antisunward and dawnward in conjunction with the motion of the ionospheric footprint of the LENA cusp signal. The Tsyganenko-96 model shows that the possible source location of the LENA cusp signals maps to the FUV spot. Considering the solar wind variations, we have attributed this "moving proton auroral spot" to a moving flux tube that was created by transient reconnection on the dayside magnetopause and contained relatively high proton densities. Copyright 2008 by the American Geophysical Union.