Continuous measurements of subglacial methane using a low-cost low-power metal oxide sensor system at the Greenland Ice Sheet

Abstract:

Constraining the various sources and sinks of the global methane (CH₄) budget is becoming an increasingly important parameter in mitigating climate change. CH₄ emissions to the atmosphere from the subglacial domain of the Greenland Ice Sheet (GrIS) have recently been documented by independent research groups [1,3]. The spatiotemporal understanding of the previously unknown cryospheric CH₄ source is still limited to two known locations along the entire margin of the GrIS and important knowledge gaps exist concerning the magnitude and seasonal variations in CH₄ emissions, biogeochemical drivers for the total emissions. To advance our understanding of this CH4 flux long term measurements are needed at more locations.

In a recent study [2], we tested the performance of a low-cost and low-power methane (CH₄) sensing system prototype based on a metal oxide sensor (MOS) sensitive to CH₄ in a natural CH₄ emitting environment at the Greenland Ice sheet (GrIS). The performance of the MOS was evaluated on basis of simultaneous measurements using a cavity ringdown spectroscopy (CRDS) reference instrument for CH₄ over a field calibration period of approximately 100 h. Results from the field calibration period show that the absolute concentration difference between the MOS and the CRDS reference values within the measured concentration range of approximately 2-100 ppm CH4 were generally lower than 5 ppm CH₄, while the relative concentration deviations between the MOS and the CRDS were generally below 10 %.

The study demonstrates how the low cost MOS technology can be an important tool for enhancing our scientific understanding of the subglacial CH4 flux to the atmosphere and the climatic feedbacks from the cryosphere to the atmosphere. We conclude that the use of CH₄ sensitive MOS can be an important supplementary measurement technique for monitoring CH₄ emissions from the subglacial domain at the GrIS and other glaciers and ice sheets around the globe.

References:

[1] Christiansen and Jørgensen (2018) https://doi.org/10.1038/s41598-018-35054-7

[2] Jørgensen et al (2020) https://doi.org/10.5194/amt-13-3319-2020

[3] Lamarche-Gagnon et al (2018) https://doi.org/10.1038/s41586-018-0800-0