Application Note: Airborne Spectrometers Monitor Volcanic Emissions

Flying into the maws of active volcanoes, spectrometers from Ocean Optics will help scientists study the effects of eruptions on climate.

As part of the Trail by Fire project, the Flame miniature spectrometers will be flown directly below volcano plumes aboard unmanned aerial vehicles (UAVs). They will take differential optical absorption spectrometry (DOAS) measurements to quantify sulfur dioxide (SO₂) levels.

The Flame spectrometers will fly aboard TurboAce Matrix unmanned aerial vehicles. Courtesy of Ocean Optics.

The Trail by Fire project aims to study volcanoes in the Andes mountains running through Chile and Peru. The six-member team of volcanologists will use the flying spectrometers as well as a specially outfitted Land Rover Defender 110 to reach some of the most remote and hard-to-study volcanoes on Earth.

Ocean Optics said the Flame's small size and low weight (265 g) were key factors in its selection, as payload weight, always an important consideration for UAVs, is especially critical at high altitude.

The Trail by Fire team, from left to right, includes Philipson Bani, Ian Schipper, Aaron Curtis, Talfan Barnie, Nial Peters and Yves Moussallam. Courtesy of Ocean Optics.

The spectrometer also offers the high resolution and thermal stability required for DOAS measurement, allowing the team to measure very small fluctuations in SO₂ content. The spectrometers are controlled by the UAV's onboard microprocessor, integrated with Ocean Optics' open-source SeaBreeze drivers.

Spectra collected by the spectrometer are saved to the UAV's onboard memory and wirelessly beamed back to the ground station. This real-time feedback allows the team to verify operation and make measurement adjustments as the UAV is in flight. The spectrometer's modular design, with interchangeable slits to adjust resolution and throughput, will enable the team to respond quickly and easily to changing conditions in the field.

Ocean Optics spectrometers have also been used in studying pyrotechnics, muzzle flashes from rifles, rocket plume emissions and applications involving flame analysis of metals and other materials.

Crowcon Detection Instruments, Ocean Optics’ sister company, also provided personal gas monitors that will alert the team to any potential danger as they collect samples of toxic volcanic gases.

The expedition is funded by a £30,000 (about $45,248) grant from Land Rover. To track its progress, visit www.trailbyfire.org.