Development of a drone-based measurement system for real-time monitoring of volcanic gas composition at Etna volcano

Volcanic gas emissions provide important insights into magmatic processes beneath the Earth's surface and play a crucial role in assessing volcanic hazards. Depending on their solubility in magma and the respective pressure conditions, volcanic gases are exsolved and released at different depths of a volcanic vent.^[1] To study behavior prior to an eruption in hazardous locations, unmanned aerial vehicles (UAVs) offer a safer measurement platform. To increase monitoring frequency, reduce manual labor and the associated risk for the researcher, this work aims to develop a drone station capable of autonomous measurement flights near the volcanic crater. The sensor system consisting of a SO₂ and CO₂ sensor was developed in-house and can be attached to the drone.^[2]
To ensure reliable and robust measurement results, a dedicated calibration station was designed and built that allows for easy, repeatable, and automated calibration of the sensor system. The system comprises a pressurized gas container with a calibration gas mixture that connects to a capillary acting as a flow limiter as well as dilution air controlled by a mass flow controller that can be adjusted to a defined concentration for sensor calibration at ambient conditions (p, T, RH).
In order to capture the dynamic behavior of volcanic gas plumes, the UAV-based point measurements are supplemented by a lightweight spectrometer based on a mobile DOAS system.^[3] This combination is intended to enable spatially resolved measurements of gas concentrations and fluxes in rapidly changing plume geometries. In the long term, the installation of an autonomous drone docking and charging station at Mount Etna is planned, allowing repeated automated measurement flights and near real-time data acquisition.

[1] H. Sigurdsson, B. F. Houghton, S. R. McNutt, H. Rymer, J. Stix, The encyclopedia of volcanoes, Elsevier/AP, Academic Press Is An Imprint Of Elsevier, Amsterdam Boston, 2015.
[2] N. Karbach, N. Bobrowski, T. Hoffmann, “Observing volcanoes with drones: studies of volcanic plume chemistry with ultralight sensor systems” Sci Rep 2022, 12, 17890.
[3] J. Kuhn, N. Bobrowski, T. Wagner, U. Platt, “Mobile and high-spectral-resolution Fabry–Pérot interferometer spectrographs for atmospheric remote sensing” Atmospheric Measurement Techniques 2021, 14, 7873–7892.