A Newly Developed Tolles-Lawson Compensation Model Accounting for Eddy-Current Dynamic Response.

Aeromagnetic compensation mitigates the aircraft-induced magnetic interference in airborne magnetometer measurements, thereby providing the measurement accuracy required by geomagnetic navigation and aeromagnetic surveying. The most widely used compensation framework, the conventional Tolles-Lawson (T-L) model, approximates the eddy-current magnetic field as an instantaneous linear response to the rate of change of the external magnetic field. Our analysis demonstrates that this assumption becomes invalid when the structural characteristic time scale is comparable to the aircraft maneuver time scale. We therefore generalize the eddy-current term into a first-order dynamic element, resulting in a dynamic eddy-current T-L model in which the eddy-current response is no longer instantaneous, while the 18-term design-matrix structure is preserved and no additional parameters are introduced. Utilizing a public flight dataset, we compare the two models on independent validation flight lines with a single calibration segment. Ridge regression on the Mag 4 channel yields a consistent and statistically significant improvement, where the median enhancement in the high-dynamic flight lines reaches +1.177 nT, approximately 70 times greater than that observed in regular survey lines. This benefit arises precisely under the high-dynamic flight conditions that are most critical for geomagnetic navigation, and its robustness is confirmed by dual-reference, vector-input, and regularization-parameter analyses.