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Sensitivity of Simulated Fire-Generated Circulations to Fuel Characteristics During Large Wildfires
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  • Matthew Roberts,
  • Neil Lareau,
  • Timothy W Juliano,
  • Kasra Shamsaei,
  • Hamed Ebrahimian,
  • Branko Kosovic
Matthew Roberts
University of Nevada, Reno

Corresponding Author:[email protected]

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Neil Lareau
University of Nevada, Reno
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Timothy W Juliano
National Center for Atmospheric Research
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Kasra Shamsaei
University of Nevada, Reno
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Hamed Ebrahimian
University of Nevada, Reno
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Branko Kosovic
National Center for Atmospheric Research (UCAR)
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Abstract

Coupled fire-atmosphere models often struggle to simulate important fire processes like fire generated flows, deep flaming fronts, extreme updrafts, and stratospheric smoke injection during large wildfires. This study uses the coupled fire-atmosphere model, WRF-Fire to examine the sensitivities of some of these phenomena to the modeled surface fuel load. Specifically, the 2020 Bear Fire and 2021 Caldor Fire in California’s Sierra Nevada are simulated using three fuel loading scenarios (1x, 4x, and 8x LANDFIRE derived surface fuel), while controlling the fire rate of spread, to isolate the fuel loading needed to produce fire-generated flows and plume rise comparable to NEXRAD radar observations of these events. Increasing fuel loads and corresponding fire residence time in WRF-Fire leads to deep plumes in excess of 10 km, strong vertical velocities of 40-45 m s-1, and combustion fronts several kilometers in width (in the along wind direction). These results indicate that LANDFIRE-based surface fuel loads in WRF-Fire likely under-represent fuel loading, having significant implications for simulating landscape-scale wildfire processes, associated impacts on spread, and fire-atmosphere feedbacks.
18 Aug 2023Submitted to ESS Open Archive
21 Aug 2023Published in ESS Open Archive