Dependence of the location of the Martian magnetic lobes on the interplanetary magnetic field direction: Observations from Mars Global Surveyor

摘要

We use magnetometer data from the Mars Global Surveyor (MGS) spacecraft during portions of the premapping orbits of the mission to study the variability of the Martian-induced magnetotail as a function of the orientation of the interplanetary magnetic field (IMF). The time spent by MGS in the magnetotail lobes during periods with positive solar wind flow-aligned IMF component B_‖~(IMF) suggests that their location as well as the position of the central polarity reversal layer (PRL) are displaced in the direction antiparallel to the IMF cross-flow component B_⊥~(IMF). Analogously, in the cases where B_‖~(IMF) is negative, the lobes are displaced in the direction of B_⊥~(IMF). This behavior is compatible with a previously published analytical model of the IMF draping, where for the first time, the displacement of a complementary reversal layer (denoted as IPRL for inverse polarity reversal layer) is deduced from first principles.