Reconciling Assumptions in Bottom-up and Top-down Approaches for Estimating Aerosol Emission Rates from Wildland Fires using Observations from FIREX-AQ

• Published in: Journal of geophysical research. Atmospheres 2021-12, Vol.126 (24), p.e2021JD035692-n/a
• Main Authors: Wiggins, E B, Anderson, B E, Brown, M D, Campuzano-Jost, P, Chen, G, Crawford, J, Crosbie, E C, Dibb, J, Digangi, J P, Diskin, G S, Fenn, M, Gallo, F, Gargulinski, E M, Guo, H, Hair, J W, Halliday, H S, Ichoku, C, Jimenez, J L, Jordan, C E, Katich, J M, Nowak, J B, Perring, A E, Robinson, C E, Sanchez, K J, Schueneman, M, Schwarz, J P, Shingler, T J, Shook, M A, Soja, A J, Stockwell, C E, Thornhill, K L, Travis, K R, Warneke, C, Winstead, E L, Ziemba, L D, Moore, R H
• Format: Article
• Language: English
• Subjects: Abrupt/Rapid Climate Change; Aerosols; Aerosols and Particles; Air pollution; Air quality; Air/Sea Constituent Fluxes; Air/Sea Interactions; Airborne sensing; Atmospheric; Atmospheric chemistry; Atmospheric composition; Atmospheric Composition and Structure; Atmospheric Effects; Atmospheric Processes; Avalanches; Benefit‐cost Analysis; Biogeosciences; Climate and Interannual Variability; Climate change; Climate Change and Variability; Climate Dynamics; Climate Impact; Climate Impacts; Climate prediction; Climate Variability; Climatology; Composition and Chemistry; Computational Geophysics; Cryosphere; Decadal Ocean Variability; Disaster Risk Analysis and Assessment; Earth Resources And Remote Sensing; Earth System Modeling; Earthquake Ground Motions and Engineering Seismology; Effusive Volcanism; Emission inventories; Emissions; Estimates; Explosive Volcanism; Fire in the Earth System; Fires; General Circulation; Geodesy and Gravity; Geological; Geophysics; Global Change; Global Change from Geodesy; Gravity and Isostasy; Hydrological Cycles and Budgets; Hydrology; Impacts of Global Change; In situ measurement; Informatics; Land/Atmosphere Interactions; Marine Geology and Geophysics; Marine Pollution; Mass Balance; Megacities and Urban Environment; Modeling; Mud Volcanism; Natural Hazards; Numerical Modeling; Numerical Solutions; Ocean influence of Earth rotation; Ocean Monitoring with Geodetic Techniques; Ocean/Atmosphere Interactions; Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions; Oceanic; Oceanography: Biological and Chemical; Oceanography: General; Oceanography: Physical; Oceans; Paleoceanography; Physical Modeling; Plumes; Policy Sciences; Pollution: Urban and Regional; Pollution: Urban, Regional and Global; Radio Oceanography; Radio Science; Regional Climate Change; Regional Modeling; Remote sensing; Resolution; Risk; Sea Level Change; Sea Level: Variations and Mean; Seismology; Smoke; Smoke plumes; Solid Earth; Statistical methods; Surface Waves and Tides; Temporal resolution; Theoretical Modeling; Troposphere: Composition and Chemistry; Tsunamis and Storm Surges; Urban Systems; Volcanic Effects; Volcanic Hazards and Risks; Volcano Monitoring; Volcano Seismology; Volcano/Climate Interactions; Volcanology; Water Cycles; Wildfires; Wildland Fire Model
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1029/2021JD035692

Accurate fire emissions inventories are crucial to predict the impacts of wildland fires on air quality and atmospheric composition. Two traditional approaches are widely used to calculate fire emissions: a satellite-based top-down approach and a fuels-based bottom-up approach. However, these methods often considerably disagree on the amount of particulate mass emitted from fires. Previously available observational datasets tended to be sparse, and lacked the statistics needed to resolve these methodological discrepancies. Here, we leverage the extensive and comprehensive airborne in situ and remote sensing measurements of smoke plumes from the recent Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) campaign to statistically assess the skill of the two traditional approaches. We use detailed campaign observations to calculate and compare emission rates at an exceptionally high-resolution using three separate approaches: top-down, bottom-up, and a novel approach based entirely on integrated airborne in situ measurements. We then compute the daily average of these high-resolution estimates and compare with estimates from lower resolution, global top-down and bottom-up inventories. We uncover strong, linear relationships between all of the high-resolution emission rate estimates in aggregate, however no single approach is capable of capturing the emission characteristics of every fire. Global inventory emission rate estimates exhibited weaker correlations with the high-resolution approaches and displayed evidence of systematic bias. The disparity between the low resolution global inventories and the high-resolution approaches is likely caused by high levels of uncertainty in essential variables used in bottom-up inventories and imperfect assumptions in top-down inventories. Plain Language Summary Smoke emitted by wildland fires is dangerous to human health and contributes to climate change.To predict and evaluate the impacts of fires, we need to know how much smoke is emitted into the atmosphere. There are two state-of-the-art methods used to estimate the mass of smoke emitted by fires, but they often disagree. In this study, we use unusually detailed measurements collected using an aircraft that flew within wildland fire smoke plumes to calculate the amount ofsmoke emitted from fires in the Western United States. We compare emission rates derived from the exceptionally high spatial and temporal resolution approach to the two tradi