Processing of a Multi-Sensor Drone-Towed Gradiometry Survey from Arctic Norway

Near-earth UAV magnetic surveying has recently become a competitive approach to traditional approaches. UAV surveys can safely and cost-effectively be conducted with a dense line spacing while tightly draping the topography, significantly improving the data resolution. For UAV magnetic surveying, the sensors are often placed in a gradiometer system towed underneath the UAV and far away from any onboard electronics to minimise the magnetic noise. In gradiometry surveys, even the sensor-specifics can result in line-to-line striping. In addition, imperfect draping and orientational deviations from the set survey heading will also result in line-to-line striping. This study discusses the processing of a multi-sensor UAV-towed magnetic survey. The raw total-field data and the across-, along-, and vertical-track differences (gradients) show significant line-to-line striping. The proposed processing method relies on modelling the along-track differences using an equivalent sources model to remove the noise responses from both sensor-specific noise and noise responses from attitude/attitude deviations. After the processing, the modelled differences show significantly less line-to-line striping. The results suggest that filter and edge detection methods can be used after the proposed processing method to locate the edge of structures that might host mineral pockets.