The fitting of a dipolar magnetic field by a dipole model

Many planets, including 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 optimum parameter sets. To address this fitting dilemma, a current loop model was recently developed by Rong et al.(2021). This technique can separate and invert the loop parameters successively. Here, we further show how this technique can be reduced and modified to fit a dipole model. The applications of this reduced technique to the model of the International Geomagnetic Reference Field 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. This technique's potential impact 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.