Solar wind electron precipitation into the dayside Martian upper atmosphere through the cusps of strong crustal fields

Measurements made by the magnetometer/electron reflectometer on board the Mars Global Surveyor spacecraft have shown spatially localized enhancements in electron fluxes over the strong crustal fields on both the dayside and night, which are used to identify the cusps in between the closed magnetic fields. This paper provides a comprehensive statistical study on the occurrence rate of dayside solar wind/magnetosheath precipitation over the strong crustal fields. Also, the occurrence rate's dependence on the magnetic elevation angles and the solar zenith angle is presented. A seasonal variation of the precipitation is also expected and found, due to both the tilt and the orbital eccentricity of Mars. The maximum occurrence rate is 40%, when the solar zenith angles are small and the magnetic fields are nearly vertical. Finally, the energy flux deposition of the solar wind electrons is calculated as well, which is 0.1%-2% of solar EUV flux input.