3D Magnetization Inversion With Significant Remanence at Low Latitudes Using Modified Normalized Source Strength

ABSTRACT I present a quantitative interpretation approach for low‐latitude remanent magnetic data based on a modified normalized source strength (MNSS) inversion. Compared with conventional normalized source strength (NSS), MNSS remains numerically stable at low magnetic latitudes and even near the equator, where NSS often becomes unstable and may lead to unreliable inversion results. However, the amplitude of MNSS is generally lower than that of NSS, which may result in underestimation of magnetic susceptibility or magnetization intensity in the recovered models. Because the MNSS forward operator does not admit a spatial integral expression, I construct an approximate forward operator by scaling the NSS operator according to the theoretical relationship between MNSS and NSS. The resulting inverse problem is solved using a reweighted regularized conjugate‐gradient (RRCG) algorithm. Synthetic examples and a field data application demonstrate that the proposed MNSS inversion can stably and effectively recover the distribution of remanent magnetization in low‐latitude environments, providing a practical tool for magnetic interpretation in complex geomagnetic settings. Moreover, for field data, the structural trends of the recovered sources are more consistent with geological interpretations than those obtained from total magnetic amplitude (Ta).