The fitting of a dipolar magnetic field by a dipole model

Many planets, including the Earth, possess a global dipolar magnetic field. To diagnose the interior source of the dipolar field, researchers usually adopt a dipole model consisting of six parameters to fit the observed dataset of the magnetic field. However, the simultaneous fitting of these parameters often leads to multiple local optimal parameter sets. To address this fitting dilemma, Rong ZJ et al. (2021) recently developed a current loop model. This technique can successively separate and invert the loop parameters. Here, we further show how this technique can be reduced and modified to fit a dipole model. Applications of this reduced technique to the International Geomagnetic Reference Field model and the Martian crustal field model highlight its unique ability to diagnose both the planetary global dipolar field and the local crustal field anomaly, a capability that sets it apart from existing methods. The potential impact of this technique on geomagnetism and planetary magnetism is significant, given its unique ability to diagnose both the planetary global dipolar field and the local crustal field anomaly.