Remote measurements of ion temperatures in the terrestrial magnetotail

Abstract

Time-resolved remote ion temperature measurements of the magnetosphere from 10 RE to -60 RE are presented for the first 48 h of the storm of 4-7 October 2000. Ion temperatures are calculated from Maxwellian fits to data from the Medium Energetic Neutral Atom instrument aboard the Imager for Magnetopause-to-Aurora Global Exploration spacecraft. The calculated ion temperatures in the magnetotail are consistent with in situ measurements from multiple geosynchronous spacecraft and Geotail at x = -9 RE The measurements indicate two separate instances of an earthward propagating increase in ion temperature during the storm. Ion heating is observed coincident with substorm injections at 0600 UT and 1720 UT on 4 October. At -12 R E, the remotely measured ion temperatures are consistent with predictions of a solar wind velocity correlation equation only when the solar wind-magnetospheric coupling is strong. At other times, the measured ion temperature is 2-3 times larger than the predicted value. Copyright 2008 by the American Geophysical Union.