A spherical harmonic Martian crustal magnetic field model that combines MAVEN and MGS data

This paper presents a new highly accurate Martian crustal magnetic field model (G90). Mars Global Surveyor (MGS) and Mars Atmosphere and Volatile evolution (MAVEN) satellite vector magnetic data are combined to represent the Martian crustal magnetic fields by spherical harmonic (SH) functions up to degree 90. We use the conventional least squares measure to determine the Gauss coefficients, while no regularization was applied. The internal field and external field are separated by using a new magnetic field activity proxy from MAVEN data. Dayside and nightside data selection criteria are also employed to minimize the influence of the ionospheric field. The resulting model delineates the details of the crustal field with a spatial resolution of ∼245 km at 120 km altitude. At satellite altitudes, this model shows a lower misfit than any other presented model, which indicates that this model is more reliable for studying the crustal field topology. Due to its high accuracy, this model will help to address some of the open questions about the Martian crustal field.