Imaging two geomagnetic storms in energetic neutral atoms

The IMAGE mission is the first of its kind. It is designed to comprehensively image a variety of emissions from the Earth's magnetosphere with sufficient time resolution to follow the dynamics associated with the development of magnetospheric storms. This paper describes initial observations of two qualitatively different geomagnetic storms by the IMAGE High Energy Neutral Atom imager (HENA). HENA images formed at energies between 10 and 60 keV/nucleon reveal the distribution and the evolution of energetic ion distributions as they are injected into the ring current during geomagnetic storms, drift about the Earth on both open and closed drift paths, and decay through charge exchange to pre-storm levels. Substorm ion injections are also imaged, as are regions of low altitude, high latitude ion precipitation into the upper atmosphere. Two events are discussed: one a major magnetic storm (the Bastille Day storm of July 15 and 16, 2000, Dst = -300nT), and the other, a minor storm (June 10, 2000, Dst = -55nT). The larger storm is characterized by ion injection deep into the magnetosphere (L similar to3 R-E), while the images from the minor storm are (L similar to3 R-E), while the images from the minor storm are consistent with injection to L similar to7 R-E.