Comparative Performance Analysis of Five Magnetometers for Geomagnetic Monitoring.

Magnetometers are essential for monitoring the Earth's magnetic field in applications such as geophysics, space weather, navigation, and volcanic studies. While professional-grade instruments provide high reliability, their cost limits spatial coverage, particularly in remote regions. This study presents a comparative analysis of five ground-based magnetometers deployed simultaneously at Universidad Adventista de Chile (36.64° S, 71.99° W) from 5-8 August 2025. Noise, signal stability, and response to geomagnetic variations were evaluated, emphasizing the influence of ambient temperature. Fluxgate and subsurface-deployed instruments showed higher consistency and reduced thermal sensitivity, while low-cost magneto-inductive sensors exhibited strong linear temperature dependence, sometimes with temporal delays. Inter-instrument correlation analyses highlighted performance differences and the trade-offs between cost and reliability. The results demonstrate that low-cost magnetometers, if carefully deployed and calibrated, can complement professional-grade sensors, improve spatial coverage, and provide valuable geomagnetic observations in regions with limited infrastructure and logistical constraints.