Simplified low cost ground-based Thermal InfraRed system for volcanic SO2 monitoring: Lessons Learned and Future Perspectives

Over the past few years, the development of ground-based Remote Sensing (RS) techniques has significantly enhanced our ability to monitor volcanic degassing. Among these, Thermal Infrared (TIR) imaging has emerged as a powerful tool for quantifying sulfur dioxide (SO2) flux and plume dynamics. This work summarizes a multi-year research activity (2021–2025) focused on the design, testing, and validation of a simplified TIR camera system across different field campaigns, including Etna (Italy), Stromboli (Italy), Sabancaya (Peru), Popocatépetl (Mexico) and Lastarria (Chile) volcanoes. The results, validated through cross-comparison with traditional Ultra-Violet (UV) cameras and satellite data (e.g., TROPOMI), demonstrate that TIR systems offer several advantages as temporal continuity by providing crucial measurements also during night-time, a precise plume geometry retrievals (plume height, thickness, and speed) by exploiting the high thermal contrast with background clear sky and a good cost-effectiveness ratio obtaining high accuracy in SO2 columnar abundance and flux retrieval. However, some limitations remain. TIR measurements are highly sensitive to volcanic particles (ash and water vapour) and environmental temperature fluctuations, requiring rigorous calibration and site-specific error assessment. Future developments will focus on the reduction of the effect of environment temperature, the correction of the influence of plume particles on SO2 retrievals and the use of Machine Learning (ML) for automated plume detection and real-time data processing. Such advancements will be pivotal for improving early warning systems and volcanic hazard mitigation on a global scale.