Pattern of volcanic degassing at open-vent volcanoes using TROPOMI SO2 time-series from COBRA retrievals

Sensitive and accurate detection of SO₂ from remote sensing is essential to monitor volcanic degassing. The main objective of this study is to understand the dynamics of SO₂ gas emissions at open-vent volcanoes between major eruptive events, using Sentinel-5P TROPOMI-based SO₂ measurements.

Time-series of SO₂ mass are analysed at 10 open-vent volcanoes (Ambrym, Erebus, Erta Ale, Kilauea, Masaya, Nyamuragira, Nyiragongo, Stromboli, Villarica, Yasur) using a newly developed TROPOMI SO₂ product generated by the Covariance Based Retrieval Algorithm (COBRA; Theys et al., 2021). Compared to the current operational SO₂ TROPOMI product (which uses the Differential Optical Absorption Spectroscopy technique), the COBRA dataset has improved performances and reduce both the noise and bias on the data, allowing a more refined study of degassing from open-vent volcanoes.

Time-series have been obtained for SO₂ emissions over a period from 2018 to early 2023. For the 10 selected persistently active volcanoes, the SO₂ behaviours are analysed and compared, showing cyclic and sporadic variations, as well as peaks of emission when a flank or major eruption occur. Patterns in SO₂ time-series during and between major eruptive events are discussed to assess the potential use (and limitations) of these measurements as a tool for early warning and volcanic crisis management.

Reference:

Theys, N., Fioletov, V., Li, C., De Smedt, I., Lerot, C., McLinden, C., Krotkov, N., Griffin, D., Clarisse, L., Hedelt, P., Loyola, D., Wagner, T., Kumar, V., Innes, A., Ribas, R., Hendrick, F., Vlietinck, J., Brenot, H., Van Roozendael, M. (2021). A sulfur dioxide Covariance-Based Retrieval Algorithm (COBRA): application to TROPOMI reveals new emission sources. Atmospheric Chemistry and Physics, 21(22), 16727-16744.