Modelling the atmospheric chemistry of volcanic plumes

Surl, Luke (2016) Modelling the atmospheric chemistry of volcanic plumes. Doctoral thesis, University of East Anglia.

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Abstract

Abstract
Volcanoes are the principal way by which volatiles are transferred from the
solid Earth to the atmosphere-hydrosphere system. Once released into the
atmosphere, volcanic emissions rapidly undergo a complex series of chemical
reactions. This thesis seeks to further the understanding of such processes by
both observation and numerical modelling.
I have adapted WRF-Chem to model passive degassing from Mount Etna,
the chemistry of its plume, and its influence on the wider atmosphere. This
investigation considers model plumes from the point of emission up to a day’s
travel from the vent and is able to reproduce observed phenomena of BrO
formation and O3 depletion within volcanic plumes.
The model plume influences several atmospheric chemistry systems,
including reactive nitrogen and organic chemistry. Plume chemistry is driven
by sunlight, and I examine how the modelled phenomena identified in this
investigation vary with the diurnal cycle.
In the modelled plume all of the bromine is involved in O3-destructive
cycling. When HBr is exhausted, volcanic HCl sustains the cycling. The
rate-limiting factor of this cycling, and therefore the rate of O3 destruction, is
sunlight.
I find qualitative differences between the chemistry of low and high intensity
plumes, with the bromine chemistry in the latter case being limited by O3
depletion.
This modelling investigation is complemented by an observational study of
O3 in a young Etnean plume from which I estimate the rate of in-plume O3
destruction within seconds to minutes after emission.
These investigations demonstrate that volcanic plumes can be included in
complex, 3D atmospheric chemistry models, and that the output from these can
be used to observe and quantify influences of volcanic plumes on the wider
atmosphere.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Vailele Chittock
Date Deposited: 17 Jun 2016 13:32
Last Modified: 17 Jun 2016 13:32
URI: https://ueaeprints.uea.ac.uk/id/eprint/59407
DOI:

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