How do Mercury's planetary magnetic field models compare to measurements from MESSENGER's and BepiColombo’s first flybys?

<p>Due to limited spacecraft coverage, the planetary magnetic field of Mercury was well observed only in the northern magnetosphere by the MESSENGER mission.<br />Multiple inversion methods have been applied to observational data to determine planetary magnetic field models that, each, identify a northward planetary magnetic equator offset but differ in the resulting multipole moments.<br />In the forward-modeling approach of this study, we take three different planetary magnetic field model representatives and model the resulting solar wind interaction with sets of the 8 most common interplanetary magnetic field (IMF) directions under otherwise nominal solar wind conditions.<br />We then extract the modeled magnetic fields along flyby trajectories of MESSENGER and BepiColombo that have their closest approach in the nightside regions of the southern magnetosphere.<br />By using both, MHD and hybrid models, we conclude that in these specific regions, the influence of the upstream IMF is minimal and is therefore uniquely suited to discriminate the influence of the different internal planetary magnetic field models.<br />Comparing these results with MESSENGER and BepiColombo flyby observations, we find which model is better suited to fit the observations.</p>