"This project considers what volcanoes put into our atmosphere. There are two major compelling motivations for this:
The first is that the vast quantities of gases and particles ejected by volcanoes change our atmosphere. Volcanoes put. To fully understand the chemistry of the air, it is necessary to understand what volcanoes are emitting, and what happens to these emissions after they mix with air. On geological timescales volcanoes have formed and changed the atmosphere and shaped the landscape. Large eruptions can alter the climate, while even comparatively small eruptions can be significant for local populations.
Secondly, monitoring the material that comes out of a volcano is an important tool for monitoring its activity. Changes in the quantity and chemical composition of a volcano’s output can tell us about sub-surface processes, this information can potentially be used for predicting future activity.
This type of monitoring can be performed by instruments on satellites, including TROPOMI on board the recently launched S5P. Data from such sources is of particular importance for volcanoes which have little ground-based monitoring, more likely for volcanoes that are remote and/or in less economically developed regions.
This project focuses on a few particular chemicals that are present in volcanic plumes – chemicals containing bromine and/or chlorine atoms. These chemicals undergo complex series of reactions when volcanic gases mix with air. One significant impact of these reactions is that ozone – an important gas for atmospheric chemistry – is consumed. The current level of scientific understanding of these processes in volcanic plumes is moderate, although the important chemical reactions are mostly known, there are several unknowns as to what effects this chemistry has in the “real world”.
Only one bromine chemical – bromine monoxide (BrO) - can be easily detected by satellites and other remote techniques. Our current understanding of plume chemistry is insufficient to determine what fraction of bromine is present as BrO plume. Simuilar difficulties underlie observations of two oxidise chlorine chemicals. This limits the usefulness of these measurements for volcano monitoring.
The objective of this project is to produce a computer modelling system for the atmospheric chemistry of volcanoes, including the chemistry of halogens. This model needs to be versatile, so that emissions from almost any volcano could be simulated. We intend to use this model to make robust assessments of the chemistry occurring within plumes. As much as possible, these conclusions we make about the chemistry are to be *quantitative* rather than simply *qualitative*.
The first implementations will be a case study on a well-studied volcano that will provide opportunities to verify the performance of the model. We also wish to show how the model can be used in combination with observations from TROPOMI. We shall show the model has ""skill"" by predicting for a past event similar numbers to those from observations. After proving this skill, we will move on to ""unobservable"" aspects of volcanic plume chemistry – such as the bromine-containing chemicals other than BrO.
As well as using the model ourselves, we hope to make a tool that the scientific community can use and further adapt for further research."
