NSF Award
0503201
The understanding of the transfer of mass, momentum, and energy from the solar wind into the magnetosphere is an important problem in magnetospheric physics. The first phase of this study will focus on a long standing debate within the magnetospheric community concerning the source region of energetic ions observed in the magnetospheric cusp. One possibility is that the ions are locally accelerated in the cusp. The alternate possibility is that the ions are accelerated at the bow shock and transported into the cusp. To investigate this issue, interplanetary magnetic field lines (IMF) draped around the magnetopause will be traced back to the bow shock to establish whether or not those field lines connect to the quasi-parallel shock region. The quasi-parallel shock is a well known source for energetic ions. Some of these fully draped field lines around the magnetopause will reconnect with geomagnetic field lines and allow magnetosheath and bow shock accelerated ions to enter the cusp region. The occurrence of cusp energetic particles (CEP) events in Polar/TIMAS, CAMMICE data will be correlated with the connection of these draped field lines to the quasi-parallel bow shock region. To consider all possible connections with the quasi-parallel bow shock regions while the IMF field lines cross the magnetosheath towards the magnetopause, the path of these bow shock interception points will also be traced across the bow shock. Any connection with the quasi-parallel shock will cause energetic ions from the shock to be on IMF field lines which are subsequently connected to geomagnetic field lines. The software tools used to determine the location of the quasi-parallel shock region at the bow shock and where IMF field lines draped around the magnetopause connect to the bow shock will be made available to the public as interactive web tools.<br/><br/>The second phase will focus on the fact that there is a 40% reduction of the He2+/H+ density ratio from the magnetosheath to the low-latitude boundary layer (LLBL) for solar wind ions. A similar result has been observed for energetic ions in the cusp, suggesting a mass dependent entry process. Density ratio measurements by the Polar/TIMAS instrument in the cusp will be compared with simultaneous observations of the density ratio in the solar wind provided by the Wind/3DP measurements to document the transfer ratio of minor ions across the magnetopause.
