Wildfires as a source of airborne mineral dust – revisiting a conceptual model using large-eddy simulation (LES)
<p>Airborne mineral dust is a key player in the Earth system and shows manifold impacts on atmospheric properties such as the radiation budget and cloud microphysics. Investigations of smoke plumes originating from wildfires found significant fractions of mineral dust within these plumes –...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-08-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/18/11863/2018/acp-18-11863-2018.pdf |
| Summary: | <p>Airborne mineral dust is a
key player in the Earth system and shows manifold impacts on atmospheric
properties such as the radiation budget and cloud microphysics.
Investigations of smoke plumes originating from wildfires found significant
fractions of mineral dust within these plumes – most likely raised by
strong, turbulent fire-related winds. This study presents and revisits a
conceptual model describing the emission of mineral dust particles during
wildfires. This is achieved by means of high-resolution large-eddy simulation
(LES), conducted with the All Scale Atmospheric Model (ASAM). The impact of
(a) different fire properties representing idealized grassland and shrubland
fires, (b) different ambient wind conditions modulated by the fire's energy
flux, and (c) the wind's capability to mobilize mineral dust particles was
investigated. Results from this study illustrate that the energy release of
the fire leads to a significant increase in near-surface wind speed, which
consequently enhances the dust uplift potential. This is in particular the
case within the fire area where vegetation can be assumed to be widely
removed and uncovered soil is prone to wind erosion. The dust uplift
potential is very sensitive to fire properties, such as fire size, shape, and
intensity, but also depends on the ambient wind velocity. Although
measurements already showed the importance of wildfires for dust emissions,
pyro-convection is so far neglected as a dust emission process in
atmosphere–aerosol models. The results presented in this study can be seen
as the first step towards a systematic parameterization representing the
connection between typical fire properties and related dust emissions.</p> |
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| ISSN: | 1680-7316 1680-7324 |