Database of storm-time equatorial ion temperatures in Earth’s
magnetosphere calculated from energetic neutral atom data and case
studies showing “clearing” of hot ions from the plasma sheet
- Amy M Keesee,
- Roxanne Marie Katus,
- Matthew Floyd,
- Earl E. Scime
Abstract
Ion temperature is a key parameter that influences dynamics in the
magnetosphere, such as particle transport and wave-particle
interactions. Measurements of ion heating and energization yields
information about phenomena such as magnetic reconnection, bursty bulk
flows, and ion injections. Taking advantage of the global view provided
by energetic neutral atom imaging, a database of ion temperature maps
during geomagnetic storms occurring throughout the NASA TWINS mission
has been created. These ion temperature maps and relevant metadata are
publicly available on CDAWeb to facilitate comparison to in situ
measurements and model output, for use as boundary conditions for
simulations, and for other relevant studies. A preliminary study of
average plasma sheet ion temperatures calculated from these maps has
revealed a common occurrence of decreasing ion temperature concurrent
with a sharp negative gradient in the IMF B. Two case studies are
presented, supporting a hypothesis that substorm activity results in
injection of high temperature ions, leaving behind an interval of lower
plasma sheet temperatures.