[P-EM09] Space Weather and Space Climate

[PEM09-16] Low Energy Ion Events During Strong Storms as a Tracer of Inner Magnetosphere Dynamics

*Delores Knipp¹ (1.University of Colorado Boulder)

Keywords:Low energy ions, Inner magnetosphere, Severe storms, Decadal measurements

We discuss and describe a new machine-learning-ready data set of Defense Meteorological Satellite Program (DMSP) low-energy ions. The data set covers the high activity period of solar cycle 23. These cool ions are usually present to some degree in and near the auroral zone. However, when geomagnetic activity impulsively increases these ions precipitate at low latitudes, often between 30 to 40 degrees magnetic latitudes. During severe to extreme space weather events the ions appear in the dawn longitude and then likely corotate to other local times. This unusual location for storm-time ions indicates a dynamic and complex electric field structure in the inner magnetosphere. These ions are important because they transfer energy to the ambient ionospheric electrons enhancing the sub-auroral electron temperature peak and the intensity of associated Stable Auroral Red (SAR)-arcs, potentially into the visible range. They are also a source of ion-atom auroras at mid-latitudes. The associated observations of higher energy electrons, also measured by DMSP show unusual decreases in average energy, suggesting that low-energy electrons are also enhanced at the same locations. Storm-time penetrating electric fields are possible explanations for these events. We show storm events during which these ions appear and provide scenarios for getting the low-energy ions in place. We propose that the dawn-side, low-energy ions are an additional complementary measure of storm strength (for the Dst Index) but for the inner magnetosphere.