Statistical Study of Magnetosheath Temperatures

During times with northward IMF, the cold dense plasma sheet of the Earth shows a strong dawn-dusk asymmetry in the temperature. The population of cold-component ions in the dawn side plasma sheet, have been shown to have temperatures which are 30-40% higher compared to the corresponding ions on the dusk side. In this study, we are investigating whether the heating of the magnetosheath ions is more frequent on the dawn side because the quasi-parallel bow shock statistically occurs more often on the dawn side compared to the dusk side. By using data from THEMIS we have identified intervals where any of the five THEMIS spacecraft is in the magnetosheath, and the interplanetary magnetic field has orientation giving rise to a quasi-parallel bow shock on either flank. As upstream monitors we have used WIND, ACE, and, when possible, any of the THEMIS spacecraft.