The Induced Global Looping Magnetic Field on Mars

Abstract

Magnetic fields inconsistent with draped IMFs and crustal fields have been observed on Mars.Considering the discovery of a global looping magnetic field around the Venusian magnetotail and the similarities in the solar wind interactions between Mars and Venus, we use MAVEN observations to investigate the global looping field on Mars and its formation mechanism. It is found that a global looping field also exists on Mars; therefore, this type of global looping field is a common feature of unmagnetized planetary bodies with ionospheres and it should also exist on Titan and near-Sun comets. The comparison of the looping fields on Mars and Venus shows that the looping field is stronger on Mars. Solar wind azimuthal flows around the magnetotail towards the -E magnetotail polar region (X_MSE<0,Y_MSE=0,Z_MSE}<-1R_M) are observed. We illustrate that the looping field can be formed by bending the draped field lines with these azimuthal flows, and that these azimuthal flows are associated with heavy ion plumes along the +E direction that are expected to be stronger on Mars than Venus. The current system associated with the looping field and its possible connection with the nightside ionosphere formations and ion escapes on Mars and Venus are discussed.Mars, Venus, induced magnetosphere, looping magnetic field

The Induced Magnetosphere of Mars: Asymmetrical Topology of the Magnetic Field Lines

“…A closed field configuration arises in the E − hemisphere. According to the hybrid simulations (see also Chai et al, ), the field lines passing Mars in the E + hemisphere can also reconnect with the formation of the closed loops.…”

“…Here we observe some new features probably missed in the averaged picture obtained from the observations. Besides the clockwise rotation of the B yz vector in the center of the tail (r <∼ 1R M ) caused by draping features in the transverse direction and a reversal of the B y component in the E − hemisphere, described by as a "looping" by Chai et al (2019), we also observe that signatures of Hall currents are appearing in the thin central current sheet at Z ∼ 1-1.3 R M (Figure 3b Figures 5c, 5d, and 5f depict maps of the magnetic field and the velocity of the planetary protons obtained by the hybrid simulations with the same input parameters as in Figure 3. In the E + hemisphere a common draping of the IMF over the ionosphere occurs.…”

“…Another interesting feature is a change of sign of the cross‐flow B y −MSE component of the magnetic field in the E − hemisphere that is well seen closer to Mars (panel f). This gives the impression of the clockwise rotation of the magnetic field (Chai et al, ). A change of sign of the B y component corresponds to a wrapping of the field lines around Mars.…”

“…We investigate how the asymmetry that is related with the motional electric field propagates to the tail. Note that different features of asymmetry of the Martian magnetosphere were discussed in Inui et al (2019), Dong et al (2015), Dubinin et al (2011), Chai et al (2019, Harada et al (2015), and Modolo et al (2016). Focus of this paper is close integration of the Mars Atmosphere and Volatile EvolutioN (MAVEN) observations, hybrid simulations, and physical interpretation.…”

Characteristics of Energetic Oxygen Ions Escaping From Mars: MAVEN Observations

“…Chai et al. (2019) found that there is a global induced looping field on Mars which are associated with heavy ion plumes.…”