The Dominant Role of Crustal Fields in Structuring Electromagnetic Environment Within the Martian Dayside Magnetosphere

Although Mars lacks an intrinsic global dipole magnetic field, the existence of crustal magnetic anomalies in the southern hemisphere causes the Martian magnetosphere to have the hybrid characteristics combining Venus-like induced and Earth-like intrinsic types. However, the influence of the crustal fields on shaping the Martian dayside magnetosphere remains ambiguous. To explore this, an entirely induced magnetosphere and a hybrid magnetosphere are obtained from a Hall-magnetohydrodynamic model without and with the consideration of the crustal fields under average solar wind conditions. Simulation results reveal that the presence of the crustal fields typically enhances and twists magnetic field and associated current within the Martian hybrid magnetosphere. Accordingly, the crustal fields significantly augment the intensity of motional and Hall electric fields, from which ions tend to acquire considerably additional energy for escape. These findings provide valuable insights into the structuring of the Martian hybrid magnetosphere under the impact of the crustal fields.