Variations of the magnetic field near Mars caused by magnetic crustal anomalies

The possible avenues for photoelectron transport were determined during southern hemisphere winter at Mars by using a mapping analysis of the theoretical magnetic field. Magnetic field line tracing was performed by superposing two magnetic field models: (1) magnetic field derived from a three-dimensional (3D) self-consistent quasi-neutral hybrid model which does not contain the Martian crustal magnetic anomalies and (2) a 3D map of the magnetic field associated with the magnetic anomalies based on Mars Global Surveyor magnetic field measurements. It was found that magnetic field lines connected to the nightside of the planet are mainly channeled within the optical shadow of the magnetotail whereas magnetic field lines connected to the dayside of the planet are observed to form the remainder of the magnetosphere. The simulation suggests that the crustal anomalies create “a magnetic shield” by decreasing the region near Mars which is magnetically connected to the Martian magnetosphere. The rotation of Mars causes periodic changes in magnetic connectivity, but not to qualitative changes in the overall magnetic field draping around Mars.