Construction of an airborne chemiluminescence ozone monitor for volcanic plumes
- 1Institut für Umweltphysik, Universität Heidelberg, Deutschland (ellen.braeutigam@iup.uni-heidelberg.de)
- 2Max-Planck-Institut für Chemie (MPIC), Mainz, Germany
- 3Institute for Atmospheric and Climate Science, ETH Zürich, Zürich, Schweiz
Volcanic plumes contain traces of bromine monoxide, BrO, which catalyze destruction of ozone, O3, mixed into the plume. Therefore, local depletion of O3 in the plume could be possible. However, calculations comparing mixing with the rate of O3 destruction suggest that no significant decline in the O3 concentration should be expected. On the other hand several studies at different volcanoes have found varying degrees of O3 depletion inside the plume. So far, ozone and its concentration distribution in volcanic plumes have only been insufficiently determined. Reliable ozone measurements would make a decisive contribution to the understanding of volcanic plume chemistry.
The standard technique for ambient O3 monitoring is the short-path ultraviolet (UV) absorption instrument. But in volcanic plumes this technique suffers from strong interference of the overlapping SO2 absorption features in the UV. SO2 is one of the major compounds in volcanic plumes.
We want to overcome this problem by relying on the chemiluminescence (CL) reaction between ozone and ethene, a standard technique for O3 measurement in the 1970s and 1980s, which we found to have no interference from trace gases abundant in volcanic plumes. The key component of a CL O3-instrument is a reaction chamber, where ethene is mixed into the ambient air and a photomultiplier tube detects the resulting photons.
Field measurements with existing CL O3-monitors are complicated, because they are usually heavy and bulky. Therefore we designed a more compact and lightweight version (10 kg backpack size CL instrument), which was used in a field study at Mount Etna. However, the campaign was restricted to plumes that are pushed down to ground in areas accessible by foot.
Here we report on a further improved version of the instrument weighing around 1 kg, which we can mount onto a drone to carry it into the plume. In particular, we describe the design advances making the reduction in weight and size possible.
How to cite: Bräutigam, E., Bobrowski, N., Kuhn, J., Rüth, M., Fuchs, C., and Platt, U.: Construction of an airborne chemiluminescence ozone monitor for volcanic plumes, DACH2022, Leipzig, Deutschland, 21–25 Mar 2022, DACH2022-80, https://doi.org/10.5194/dach2022-80, 2022.
