Microwave Limb Sounder (MLS) observations of biomass burning products in the stratosphere from Canadian forest fires in August 2017
<p>Forest fires in British Columbia in August 2017 caused a pyrocumulonimbus event that injected a polluted air mass into the lower stratosphere. The Microwave Limb Sounder (MLS) on the Aura satellite first observed the polluted air mass on 14 August 2017 and continued to observe it for 60 d (...
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| Autores principales: | , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Copernicus Publications
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/1b1dff1cb34c49f5ad2d89a78b4f96e1 |
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| Sumario: | <p>Forest fires in British Columbia in August 2017 caused a
pyrocumulonimbus event that injected a polluted air mass into the
lower stratosphere. The Microwave Limb Sounder (MLS) on the Aura
satellite first observed the polluted air mass on 14 August 2017 and
continued to observe it for 60 d (100 d in water vapour). We
estimate the mass of CO injected into the stratosphere to be
2400 Gg. Events in which a fire injects its burning products
directly into the stratosphere are rare: this is the third of four
such events in the 16 years since the launch of Aura, the
second largest of the four events, and the only one in the Northern
Hemisphere. The other three events occurred in Australia in December
2006, February 2009 and from December 2019 to January 2020. Unlike
the 2006 and 2009 events, but like the 2019–2020 event, the polluted
air mass described here had a clearly elevated water vapour content:
between 2.5 and 5 times greater than that in the surrounding
atmosphere. We describe the evolution of the polluted air mass,
showing that it rose to an altitude of about 24 km (31 hPa) and
divided into several identifiable parts. In addition to CO and
H<span class="inline-formula"><sub>2</sub></span>O, we observe enhanced amounts of HCN, CH<span class="inline-formula"><sub>3</sub></span>CN, CH<span class="inline-formula"><sub>3</sub></span>Cl and
CH<span class="inline-formula"><sub>3</sub></span>OH with mixing ratios in the range to be expected from a
variety of measurements in other biomass burning plumes. We use
back trajectories and plume-dispersion modelling to demonstrate that
the pollutants observed by MLS originated in the British Columbia
fires, the likeliest source being at 53.2<span class="inline-formula"><sup>∘</sup></span> N, 121.8<span class="inline-formula"><sup>∘</sup></span> W
at 05:20 UTC on 13 August 2017.</p> |
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