1. High-resolution simulations of the spread of volcanic gases
Burton, R. R.1 , Bauguitte, S.2, Brooks, B.1, Burton, M.3, Colfescu, I.1, Ilinskaya, E.4, Lee, J.1, Mobbs, S. D.1 ,
Petersen, G. N.5, Pardini, F.3, Pfeffer, M.5, Welpott, A.2
1 NCAS 2 FAAM 3 School of Earth and Environmental Sciences, University of Manchester
4 School of Earth and Environment, University of Leeds 5 Icelandic Met Office
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Introduction
In 2015 NCAS became aware of attempts to detect and quantify CO2 emissions from non-erupting volcanoes in Iceland using ground-based surveys. These surveys were slow and ineffective but it was realised that the analysis techniques developed during the Elgin response (Lee et al. 2018) could be used to quantify CO2 emissions from such volcanoes.
In 2016/2017 FAAM/NCAS flew missions in Iceland and detected large CO2 plumes from several points around the Katla volcano. It is hypothesised that fluctuations in the rate of degassing of volcanoes may be used as an indicator of forthcoming eruptions. Knowing the source of the emissions is vital. A B
Observed CO2 from FAAM aircraft in Plumes A and B are discussed below. B
Dense gas model
Location. Models such as HYSPLIT do not capture the complex dynamics associated with flow over mountainous terrain, such as found in Iceland. Instead, the dense gas WRF model (Burton et al. 2017) was used. This has previously been applied to the Lake Nyos disaster (see right), where the location of the CO2 release was known. In Iceland, the location(s) are unknown.
Simulated CO2 from the Lake Nyos release, showing major rivers and the subsequent spread of CO2 and pooling of CO2 in the major valley systems.
Determining the location of the Iceland sources
I. Gas is transported
westward through a narrow channel
II. Gas pools in certain areas, determined by terrain
III. Wind turns to westerly
Initially, all known volcanoes (active and dormant), in addition to river outlets, were included as potential sources in the simulations.
Then, further analysis suggested which location(s) were likely to be actual sources. The single source shown here is on the Katla glacier.
The simulated gas dispersion can be compared to that from aircraft observations, and good agreement is found.
When numerous flights are analysed together, a diagram can be constructed which shows the most likely source of the emissions.
FLIGHTS B987,
B989, C060
FAAM flights have detected CO2 plumes In Iceland on numerous occasions.
Simulated plume locations produce agreement with observations,
given an appropriate choice of source location.
Simulations suggest the most likely source of the emissions.
Paper has been submitted to GRL.
Summary
Likely source region
for C060 plumes
Likely source region
for B987 plumes
Likely source region for
B989 plumes NN
= potential source
References. Burton et al. (2017). The use of a numerical weather prediction model to simulate the release of a dense gas with an application to the Lake Nyos disaster of Meteorological Applications, 24(1). Lee, J. et al. (2018). Flow rate and source reservoir identification from airborne chemical sampling of the uncontrolled Elgin platform gas release. Atmospheric Measurement Techniques. doi: amt