TY - JOUR
T1 - Investigating Carbonaceous Aerosol and Its Absorption Properties From Fires in the Western United States (WE‐CAN) and Southern Africa (ORACLES and CLARIFY)
AU - Carter, Therese S.
AU - Heald, Colette L.
AU - Cappa, Christopher D.
AU - Kroll, Jesse H.
AU - Campos, Teresa L.
AU - Coe, Hugh
AU - Cotterell, Michael I.
AU - Davies, Nicholas W.
AU - Farmer, Delphine K.
AU - Fox, Cathyrn
AU - Garofalo, Lauren A.
AU - Hu, Lu
AU - Langridge, Justin M.
AU - Levin, Ezra J. T.
AU - Murphy, Shane M.
AU - Pokhrel, Rudra P.
AU - Shen, Yingjie
AU - Szpek, Kate
AU - Taylor, Jonathan W.
AU - Wu, Huihui
N1 - Funding Information:
This research has been supported by the NOAA Climate Program Office, NA16OAR4310112 for T. S. Carter, C. L. Heald, and J. H. Kroll; NA16OAR4310111 for C. D. Cappa; and NA17OAR4310010 for L. A. Garofalo, E. J. T. Levin, D. K. Farmer and by NSF, #AGS‐1650786 for E. J. T. Levin; #AGS‐1650275 for L. Hu; and #AGS‐1650493 for S. M. Murphy and R. P. Pokhrel. We acknowledge the Natural Environmental Research Council (NERC) (grant NE/L013479/1) for funding the measurements performed during CLARIFY‐2017. We thank everyone involved in the planning and execution of the CLARIFY‐2017 project. The BAe‐146‐301 atmospheric research aircraft was flown by Airtask and managed by the Facility for Airborne Atmospheric Measurements (FAAM), which is a joint entity of NERC and the Met Office. The authors thank Armin Wisthaler and Tomas Mikoviny for acetonitrile measurements from both ARCTAS and DC3, Wade Permar for acetonitrile measurements during WE‐CAN, and Paul DeMott and Sonia Kreidenweis for carbonaceous aerosol mass concentration measurements during WE‐CAN. We thank James Podolske and Steven Howell for measurements during ORACLES. We acknowledge data from the IMPROVE network. IMPROVE is a collaborative association of state, tribal, and federal agencies and international partners. The US Environmental Protection Agency is the primary funding source, with contracting and research support from the National Park Service. The Air Quality Group at the University of California, Davis, is the central analytical laboratory, with ion analysis provided by Research Triangle Institute and carbon analysis provided by Desert Research Institute.
Funding Information:
This research has been supported by the NOAA Climate Program Office, NA16OAR4310112 for T. S. Carter, C. L. Heald, and J. H. Kroll; NA16OAR4310111 for C. D. Cappa; and NA17OAR4310010 for L. A. Garofalo, E. J. T. Levin, D. K. Farmer and by NSF, #AGS-1650786 for E. J. T. Levin; #AGS-1650275 for L. Hu; and #AGS-1650493 for S. M. Murphy and R. P. Pokhrel. We acknowledge the Natural Environmental Research Council (NERC) (grant NE/L013479/1) for funding the measurements performed during CLARIFY-2017. We thank everyone involved in the planning and execution of the CLARIFY-2017 project. The BAe-146-301 atmospheric research aircraft was flown by Airtask and managed by the Facility for Airborne Atmospheric Measurements (FAAM), which is a joint entity of NERC and the Met Office. The authors thank Armin Wisthaler and Tomas Mikoviny for acetonitrile measurements from both ARCTAS and DC3, Wade Permar for acetonitrile measurements during WE-CAN, and Paul DeMott and Sonia Kreidenweis for carbonaceous aerosol mass concentration measurements during WE-CAN. We thank James Podolske and Steven Howell for measurements during ORACLES. We acknowledge data from the IMPROVE network. IMPROVE is a collaborative association of state, tribal, and federal agencies and international partners. The US Environmental Protection Agency is the primary funding source, with contracting and research support from the National Park Service. The Air Quality Group at the University of California, Davis, is the central analytical laboratory, with ion analysis provided by Research Triangle Institute and carbon analysis provided by Desert Research Institute.
Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.
PY - 2021/8/16
Y1 - 2021/8/16
N2 - Biomass burning (BB) produces large quantities of carbonaceous aerosol (black carbon and organic aerosol, BC and OA, respectively), which significantly degrade air quality and impact climate. BC absorbs radiation, warming the atmosphere, while OA typically scatters radiation, leading to cooling. However, some OA, termed brown carbon (BrC), also absorbs visible and near UV radiation; although, its properties are not well constrained. We explore three aircraft campaigns from important BB regions with different dominant fuel and fire types (Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen [WE-CAN] in the western United States and ObseRvations of Aerosols above CLouds and their intEractionS and Cloud-Aerosol-Radiation Interactions and Forcing for Year downwind of southern Africa) and compare them with simulations from the global chemical transport model, GEOS-Chem using GFED4s. The model generally captures the observed vertical profiles of carbonaceous BB aerosol concentrations; however, we find that BB BC emissions are underestimated in southern Africa. Our comparisons suggest that BC and/or BrC absorption is substantially higher downwind of Africa than in the western United States and, while the Saleh et al. (2014, https://doi.org/10.1038/ngeo2220) and FIREX parameterizations based on the BC:OA ratio improve model-observation agreement in some regions, they do not sufficiently differentiate absorption characteristics at short wavelengths. We find that photochemical whitening substantially decreases the burden and direct radiative effect of BrC (annual mean of +0.29 W m
−2 without whitening and +0.08 W m
−2 with). Our comparisons suggest that whitening is required to explain WE-CAN observations; however, the importance of whitening for African fires cannot be confirmed. Qualitative comparisons with the OMI UV aerosol index suggest our standard BrC whitening scheme may be too fast over Africa.
AB - Biomass burning (BB) produces large quantities of carbonaceous aerosol (black carbon and organic aerosol, BC and OA, respectively), which significantly degrade air quality and impact climate. BC absorbs radiation, warming the atmosphere, while OA typically scatters radiation, leading to cooling. However, some OA, termed brown carbon (BrC), also absorbs visible and near UV radiation; although, its properties are not well constrained. We explore three aircraft campaigns from important BB regions with different dominant fuel and fire types (Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen [WE-CAN] in the western United States and ObseRvations of Aerosols above CLouds and their intEractionS and Cloud-Aerosol-Radiation Interactions and Forcing for Year downwind of southern Africa) and compare them with simulations from the global chemical transport model, GEOS-Chem using GFED4s. The model generally captures the observed vertical profiles of carbonaceous BB aerosol concentrations; however, we find that BB BC emissions are underestimated in southern Africa. Our comparisons suggest that BC and/or BrC absorption is substantially higher downwind of Africa than in the western United States and, while the Saleh et al. (2014, https://doi.org/10.1038/ngeo2220) and FIREX parameterizations based on the BC:OA ratio improve model-observation agreement in some regions, they do not sufficiently differentiate absorption characteristics at short wavelengths. We find that photochemical whitening substantially decreases the burden and direct radiative effect of BrC (annual mean of +0.29 W m
−2 without whitening and +0.08 W m
−2 with). Our comparisons suggest that whitening is required to explain WE-CAN observations; however, the importance of whitening for African fires cannot be confirmed. Qualitative comparisons with the OMI UV aerosol index suggest our standard BrC whitening scheme may be too fast over Africa.
U2 - 10.1029/2021jd034984
DO - 10.1029/2021jd034984
M3 - Article
SN - 2169-8996
VL - 126
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
IS - 15
M1 - e2021JD034984
ER -