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Informed Multi-scale Approach Applied to the British Columbia Fires of Late Summer 2017
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  • Jon M. Reisner,
  • Alexander J. Josephson,
  • Kyle Gorkowski,
  • Eunmo Koo,
  • Daniel K. Thompson,
  • Dave Schroeder,
  • Manvendra K. Dubey
Jon M. Reisner
LANL
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Alexander J. Josephson
Los Alamos National Laboratory

Corresponding Author:[email protected]

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Kyle Gorkowski
Los Alamos National Laboratory
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Eunmo Koo
Los Alamos National Laboratory (DOE)
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Daniel K. Thompson
Natural Resources Canada
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Dave Schroeder
Province of Alberta
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Manvendra K. Dubey
Los Alamos National Laboratory (DOE)
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Abstract

Pyrocumulonimbus clouds have a complex origin depending on fire dynamics and meteorological conditions. When a pyrocumulonimbus (PyroCb) cloud formation develops and is maintained over a period of time, it can inject significant aerosol into the troposphere and lower stratosphere, resulting in longer term (months to years) climate cooling effects. In this work we investigate the British Columbia and northern Washington wildfires on August 12-13, 2017 using a multi-scale simulation framework. We use the output of a physics based wildfire model (FIRETEC) with parameterized energy, particle, and gas emissions to drive the upper atmospheric aerosol mass injection within a regional cloud resolving model (HIGRAD). We demonstrate that vertical motions produced by latent heat release of the condensation of ice and cloud particles within the PyroCbs induce another 5 km of lifting of the simulated aerosol plume. Primary black carbon and organic aerosols alone may not be enough to explain the observed aerosol burden, thus we show that dust and ash particles can enhance lofted aerosol mass. Additionally, we show that semi volatile organic gases emitted by the fires eventually condense, further increasing the aerosol burden. A simulation with all aerosol mechanisms active, driven by the observed fuel load and environmental conditions, reasonably reproduces an aerosol profile inferred from observational data.