EGU23-8160
https://doi.org/10.5194/egusphere-egu23-8160
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Bromine monoxide composition in volcanic plumes measured by S-5P/TROPOMI – Global survey of magmatic composition

Simon Warnach1,2, Christian Borger1, Nicole Bobrowski3, Holger Sihler1, Moritz Schöne1,4, Steffen Beirle1, Ulrich Platt4, and Thomas Wagner1
Simon Warnach et al.
  • 1Max Planck Institute for Chemistry, Mainz, Germany
  • 2Laboratoire de Physique et de Chimie de l’Environnement et de l’Espace, CNRS, Université d’Orléans, Orléans, France
  • 3Istituto Nazionale Geofisica e Vulcanologia, Catania, Italy
  • 4Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany

Bromine monoxide (BrO) is a halogen radical influencing atmospheric chemical processes, in particular the abundance of ozone, e. g. in the polar boundary layer and above salt lakes, in the stratosphere as well as in volcanic plumes. Furthermore, the molar bromine to sulphur ratio in volcanic gas emissions is a proxy for the magmatic composition of a volcano and potentially an eruption forecast parameter.

The high spatial resolution combined with the better signal-to-noise ratio of the S-5P/TROPOMI instrument (up to 3.5x5.5km2) and its daily global coverage offer the potential to detect BrO and its corresponding ratio with sulphur dioxide (BrO/SO2) even during minor eruptions and for continuous passive degassing volcanoes.

Here, we present a global overview of BrO/SO2 molar ratios in volcanic dispersion gas plumes derived from a systematic long-term investigation covering four years (January 2018 to December 2021) of TROPOMI data.

We retrieved column densities of BrO and SO2 using Differential Optical Absorption Spectroscopy (DOAS) and calculated mean BrO/SO2 molar ratios for various volcanoes. The calculated BrO/SO2 molar ratios differ strongly ranging from several 10-5 up to several 10-4 both between different volcanoes, but also between measurements at one volcano at different points in time. In our four-year study of S-5P/TROPOMI data we successfully recorded 4232 volcanic plumes, 3063 of which can be clearly assigned to 43 volcanoes. Subsequently, the mean BrO/SO2 ratio is calculated for these plumes - increasing the global data-base of reported BrO/SO2 ratios from 28 to 60 volcanoes. For the first time, BrO/SO2 ratios were successfully determined for six hot spot volcanoes - all of which yield low BrO/SO2 ratios between 2-5x10-5, in contrast to 2-16x10-5 for subduction zone volcanoes, suggesting a depletion of bromine in the Earth’s mantle.

In addition, time-series of the BrO/SO2 ratio were derived for 19 volcanoes, with more than 200 daily measurements of the BrO/SO2 ratio at the five volcanoes Mt. Etna, Italy, Dukono, Indonesia, Popocatepetl, Mexico, Nevado del Ruiz, Colombia, and Sangay, Ecuador.

How to cite: Warnach, S., Borger, C., Bobrowski, N., Sihler, H., Schöne, M., Beirle, S., Platt, U., and Wagner, T.: Bromine monoxide composition in volcanic plumes measured by S-5P/TROPOMI – Global survey of magmatic composition, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-8160, https://doi.org/10.5194/egusphere-egu23-8160, 2023.