Titan at the edge: 1. Titan's interaction with Saturn's magnetosphere in the prenoon sector

[1] The characteristics of Titan's environment at 09:00 Saturn local time (SLT) are studied using a three-dimensional multifluid/multiscale model of Titan embedded in a global model of Saturn's magnetosphere for three cases: a stationary magnetopause, an inward moving magnetopause, and an outward moving magnetopause. The results show that the plasma and magnetic field upstream of Titan are variable and that the variability can be enhanced when Saturn's magnetopause is not stationary. Rotating cold, interchange fingers cause rapid changes in the plasma velocity, density, and composition, while gradual changes are due to the relatively slow compression and expansion of Saturn's magnetopause. Titan enters a boundary layer on the inside of Saturn's magnetopause when Saturn's magnetopause compresses. The boundary layer is characterized by shearing flows and a mix of magnetospheric and magnetosheath plasma. The irregular flows in the boundary layer strongly modify Titan's induced magnetosphere. The results indicate that more ions from Titan are lost from Saturn's magnetosphere during parallel interplanetary magnetic field (IMF) than antiparallel IMF. In addition, we find that Titan's ion tail may be able to prevent the magnetopause from crossing Titan when Titan is in the prenoon sector. Therefore, despite a large increase in solar wind pressure, Titan remained inside of Saturn's magnetosphere. A synthetic trajectory through the simulation is shown to be consistent with magnetometer data from the TA flyby.