Magnetic Topology in the Mars Magnetosphere and Its Consequences

Abstract:

The combination of MAVEN plasma and field measurements (see Jakosky et al., 2015) and a library of data-validated models of the solar wind interaction with Mars (Ma et al., GRL, 2015; Dong et al., GRL, 2015) provides unprecedented opportunity to both probe the unique topology of the Martian magnetosphere and understand its consequences. Several investigations using these combined resources have explained observed features such as IMF-dependent distortions related to the crustal field influences in both the dayside field draping (Fang et al., GRL, 2018) and in the magnetotail (DiBraccio et al., GRL, 2018), the presence of apparently closed field lines and photoelectrons detected in the nightside magnetosphere, far above the ionosphere (Liemohn, GRL, 2007, Xu et al., JGR, 2017), patterns of observed auroral precipitation (Schneider et al., GRL, 2018), and magnetospheric field changes related to space weather events (Xu et al., JGR, 2018). Here we consider other reported observations that can be better understood by considering the field topology. One of these is the trans-terminator loops along which ionosphere pressure gradients can accelerate electrons (Harada et al., GRL 2016; Collinson et al., JGR, 2016). Another concerns reconnection both in the magnetotail (Harada et al., 2017) and between the draped interplanetary fields and the crustal fields (Harada et al., GRL, 2018). Interpretation of the complicated low energy planetary ion outflows is yet another analysis where differences between draped IMF control and (hemispherically dependent) crustal field influences come into play. The bottom line is that magnetic topology ‘situational awareness’ is essential for almost all studies of plasma science results at Mars. The challenge is how to make such information widely accessible.