Sources and characteristics of summertime organic aerosol in the Colorado Front Range: perspective from measurements and WRF-Chem modeling

R. Bahreini; R. Bahreini; R. Ahmadov; R. Ahmadov; S. A. McKeen; S. A. McKeen; K. T. Vu; J. H. Dingle; E. C. Apel; D. R. Blake; N. Blake; T. L. Campos; C. Cantrell; F. Flocke; A. Fried; J. B. Gilman; A. J. Hills; R. S. Hornbrook; G. Huey; L. Kaser; B. M. Lerner; B. M. Lerner; B. M. Lerner; R. L. Mauldin; S. Meinardi; D. D. Montzka; D. Richter; J. R. Schroeder; J. R. Schroeder; M. Stell; D. Tanner; J. Walega; P. Weibring; A. Weinheimer

doi:10.5194/acp-18-8293-2018

Atmospheric Chemistry and Physics (Jun 2018)

Sources and characteristics of summertime organic aerosol in the Colorado Front Range: perspective from measurements and WRF-Chem modeling

R. Bahreini,
R. Bahreini,
R. Ahmadov,
R. Ahmadov,
S. A. McKeen,
S. A. McKeen,
K. T. Vu,
J. H. Dingle,
E. C. Apel,
D. R. Blake,
N. Blake,
T. L. Campos,
C. Cantrell,
F. Flocke,
A. Fried,
J. B. Gilman,
A. J. Hills,
R. S. Hornbrook,
G. Huey,
L. Kaser,
B. M. Lerner,
B. M. Lerner,
B. M. Lerner,
R. L. Mauldin,
S. Meinardi,
D. D. Montzka,
D. Richter,
J. R. Schroeder,
J. R. Schroeder,
M. Stell,
D. Tanner,
J. Walega,
P. Weibring,
A. Weinheimer

Affiliations

R. Bahreini: Department of Environmental Sciences, University of California, Riverside, CA 92521, USA
R. Bahreini: Environmental Toxicology Graduate Program, University of California, Riverside, CA 92521, USA
R. Ahmadov: Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA
R. Ahmadov: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80301, USA
S. A. McKeen: Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA
S. A. McKeen: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80301, USA
K. T. Vu: Environmental Toxicology Graduate Program, University of California, Riverside, CA 92521, USA
J. H. Dingle: Environmental Toxicology Graduate Program, University of California, Riverside, CA 92521, USA
E. C. Apel: Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA
D. R. Blake: Department of Chemistry, University of California, Irvine, CA 92697, USA
N. Blake: Department of Chemistry, University of California, Irvine, CA 92697, USA
T. L. Campos: Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA
C. Cantrell: Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO 80303, USA
F. Flocke: Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA
A. Fried: Institute for Arctic and Alpine Research, University of Colorado, Boulder, CO 80303, USA
J. B. Gilman: Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA
A. J. Hills: Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA
R. S. Hornbrook: Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA
G. Huey: Department of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30033, USA
L. Kaser: Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA
B. M. Lerner: Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA
B. M. Lerner: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80301, USA
B. M. Lerner: now at: Aerodyne Research, Inc., Billerica, MA 01821, USA
R. L. Mauldin: Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO 80303, USA
S. Meinardi: Department of Chemistry, University of California, Irvine, CA 92697, USA
D. D. Montzka: Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA
D. Richter: Institute for Arctic and Alpine Research, University of Colorado, Boulder, CO 80303, USA
J. R. Schroeder: Department of Chemistry, University of California, Irvine, CA 92697, USA
J. R. Schroeder: now at: NASA Langley Research Center, Newport News, VA 23666, USA
M. Stell: Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA
D. Tanner: Department of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30033, USA
J. Walega: Institute for Arctic and Alpine Research, University of Colorado, Boulder, CO 80303, USA
P. Weibring: Institute for Arctic and Alpine Research, University of Colorado, Boulder, CO 80303, USA
A. Weinheimer: Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA

DOI: https://doi.org/10.5194/acp-18-8293-2018
Journal volume & issue: Vol. 18
pp. 8293 – 8312

Abstract

Read online

The evolution of organic aerosols (OAs) and their precursors in the boundary layer (BL) of the Colorado Front Range during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ, July–August 2014) was analyzed by in situ measurements and chemical transport modeling. Measurements indicated significant production of secondary OA (SOA), with enhancement ratio of OA with respect to carbon monoxide (CO) reaching 0.085±0.003 µg m−3 ppbv−1. At background mixing ratios of CO, up to ∼ 1.8 µg m−3 background OA was observed, suggesting significant non-combustion contribution to OA in the Front Range. The mean concentration of OA in plumes with a high influence of oil and natural gas (O&G) emissions was ∼ 40 % higher than in urban-influenced plumes. Positive matrix factorization (PMF) confirmed a dominant contribution of secondary, oxygenated OA (OOA) in the boundary layer instead of fresh, hydrocarbon-like OA (HOA). Combinations of primary OA (POA) volatility assumptions, aging of semi-volatile species, and different emission estimates from the O&G sector were used in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) simulation scenarios. The assumption of semi-volatile POA resulted in greater than a factor of 10 lower POA concentrations compared to PMF-resolved HOA. Including top-down modified O&G emissions resulted in substantially better agreements in modeled ethane, toluene, hydroxyl radical, and ozone compared to measurements in the high-O&G-influenced plumes. By including emissions from the O&G sector using the top-down approach, it was estimated that the O&G sector contributed to < 5 % of total OA, but up to 38 % of anthropogenic SOA (aSOA) in the region. The best agreement between the measured and simulated median OA was achieved by limiting the extent of biogenic hydrocarbon aging and consequently biogenic SOA (bSOA) production. Despite a lower production of bSOA in this scenario, contribution of bSOA to total SOA remained high at 40–54 %. Future studies aiming at a better emissions characterization of POA and intermediate-volatility organic compounds (IVOCs) from the O&G sector are valuable.

Published in Atmospheric Chemistry and Physics

ISSN: 1680-7316 (Print); 1680-7324 (Online)
Publisher: Copernicus Publications
Country of publisher: Germany
LCC subjects: Science: Physics; Science: Chemistry
Website: http://www.atmospheric-chemistry-and-physics.net/

About the journal