Spatially Resolved Photochemistry Impacts Emissions Estimates in Fresh Wildfire Plumes

Brett B. Palm, Qiaoyun Peng, Samuel R. Hall, Kirk Ullmann, Teresa L. Campos, Andrew Weinheimer, Deedee Montzka, Geoffrey Tyndall, Wade Permar, Lu Hu, Frank Flocke, Emily V. Fischer, Joel A. Thornton

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Wildfire emissions affect downwind air quality and human health. Predictions of these impacts using models are limited by uncertainties in emissions and chemical evolution of smoke plumes. Using high-time-resolution aircraft measurements, we illustrate spatial variations that can exist within a plume due to differences in the photochemical environment. Horizontal and vertical crosswind gradients of dilution-corrected mixing ratios were observed in midday plumes for reactive compounds and their oxidation products, such as nitrous acid, catechol, and ozone, likely due to faster photochemistry in optically thinner plume edges relative to darker plume cores. Gradients in plumes emitted close to sunset are characterized by titration of O3 in the plume and reduced or no gradient formation. We show how crosswind gradients can lead to underestimated emission ratios for reactive compounds and overestimated emission ratios for oxidation products. These observations will lead to improved predictions of wildfire emissions, evolution, and impacts across daytime and nighttime.

Original languageEnglish
Article numbere2021GL095443
JournalGeophysical Research Letters
Volume48
Issue number23
DOIs
StatePublished - Dec 16 2021

Keywords

  • biomass burning
  • fire emissions
  • hydroxyl radical
  • plume chemistry
  • plume evolution
  • wildfire

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