IMF By influence on plasma ion convection in the mid-tail in Earth’s magnetosphere

Sammanfattning: The results of past studies indicate that there is an influence of the presence of a nonzero dusk-dawn i.e. y component of the interplanetary magnetic field(IMF By) on the near-Earth magnetotail. Specifically, on the dusk-dawn component (By) of the magnetic field and plasma ion convection, resulting in interhemispheric asymmetries. This project aimed to investigate whether the same is true for mid-tail distances (around 60 RE downtail, at around the moon distance) by investigating data from the ARTEMIS P1 satellite and the OMNI IMF database. This was done by first filtering the data to only include plasma sheet data using criteria on ion temperature and density, and then constructing averages of both tail By and the ion velocity perpendicular to the magnetic field. These average were constructed separately for clearly positive IMF By (> 3 nT) and clearly negative IMF By (< -3 nT), and separately for the northern and southern plasma sheet. It was found that there is a clear effect of the sign of IMF By on both tail By and ion flows, leading to asymmetries similar to those reported at near-Earth distances. Thus it can be concluded that the presence of clearly nonzero IMF By affects the mid-tail region as well, and potentially the entire magnetotail. While these results are consistent with near-Earth studies, this is the first time the asymmetries due to nonzero IMF By are reported in the mid-tail.