Detecting and Mapping Permafrost: Preliminary Data from a Novel Frequency Domain Electromagnetic Induction Device

This paper presents preliminary findings for the innovative, lightweight, electronically bucked frequency domain In-Flight Rapid Observation and Survey Tool (iFROST) system, tailored for detecting and mapping permafrost. The system is built to be carried by a commercial, medium sized unmanned aerial system (UAS). iFROST is comprised of a tuned primary transmitter and an untuned bucking coil, currently operating at two frequencies, 93 kHz, and 330 kHz—the former being the focus of this paper. The data demonstrated here were collected over varying depth permafrost in Fox, Alaska, USA. The system was placed above the ground in 10 cm increments from 0 to 2 meters using a non-conductive test rig. For comparative purposes, data were also collected at the same 93 kHz frequency and at the same locations with identical 10 cm increments above the soil using the commercial off-the-shelf Geophex, GEM-2 system. The results show that the iFROST system provides significantly more stable and consistent data from one measurement to the next compared to the commercial system. These preliminary data, collected under actual field conditions, demonstrate the system’s robustness in predicting anomaly responses and in supporting high-fidelity, physics-based inversion algorithms for detecting and mapping permafrost in real-world environments.