TY - JOUR
T1 - A better representation of volatile organic compound chemistry in WRF-Chem and its impact on ozone over Los Angeles
AU - Zhu, Qindan
AU - Schwantes, Rebecca H.
AU - Coggon, Matthew
AU - Harkins, Colin
AU - Schnell, Jordan
AU - He, Jian
AU - Pye, Havala O.T.
AU - Li, Meng
AU - Baker, Barry
AU - Moon, Zachary
AU - Ahmadov, Ravan
AU - Pfannerstill, Eva Y.
AU - Place, Bryan
AU - Wooldridge, Paul
AU - Schulze, Benjamin C.
AU - Arata, Caleb
AU - Bucholtz, Anthony
AU - Seinfeld, John H.
AU - Warneke, Carsten
AU - Stockwell, Chelsea E.
AU - Xu, Lu
AU - Zuraski, Kristen
AU - Robinson, Michael A.
AU - Neuman, J. Andrew
AU - Veres, Patrick R.
AU - Peischl, Jeff
AU - Brown, Steven S.
AU - Goldstein, Allen H.
AU - Cohen, Ronald C.
AU - McDonald, Brian C.
N1 - Publisher Copyright:
© Author(s) 2024. This work is distributed under the Creative Commons Attribution 4.0 License.
PY - 2024/5/7
Y1 - 2024/5/7
N2 - The declining trend in vehicle emissions has underscored the growing significance of volatile organic compound (VOC) emissions from volatile chemical products (VCPs). However, accurately representing VOC chemistry in simplified chemical mechanisms remains challenging due to its chemical complexity including speciation and reactivity. Previous studies have predominantly focused on VOCs from fossil fuel sources, leading to an underrepresentation of VOC chemistry from VCP sources. We developed an integrated chemical mechanism, RACM2B-VCP, that is compatible with WRF-Chem and is aimed at enhancing the representation of VOC chemistry, particularly from VCP sources, within the present urban environment. Evaluation against the Air Quality System (AQS) network data demonstrates that our model configured with RACM2B-VCP reproduces both the magnitude and spatial variability of O3 and PM2.5 in Los Angeles. Furthermore, evaluation against comprehensive measurements of O3 and PM2.5 precursors from the Reevaluating the Chemistry of Air Pollutants in California (RECAP-CA) airborne campaign and the Southwest Urban NOx and VOC Experiment (SUNVEx) ground site and mobile laboratory campaign confirm the model's accuracy in representing NOx and many VOCs and highlight remaining biases. Although there exists an underprediction in the total VOC reactivity of observed VOC species, our model with RACM2B-VCP exhibits good agreement for VOC markers emitted from different sectors, including biogenic, fossil fuel, and VCP sources. Through sensitivity analyses, we probe the contributions of VCP and fossil fuel emissions to total VOC reactivity and O3. Our results reveal that 52ĝ€¯% of the VOC reactivity and 35ĝ€¯% of the local enhancement of MDA8 O3 arise from anthropogenic VOC emissions in Los Angeles. Significantly, over 50ĝ€¯% of this anthropogenic fraction of either VOC reactivity or O3 is attributed to VCP emissions. The RACM2B-VCP mechanism created, described, and evaluated in this work is ideally suited for accurately representing ozone for the right reasons in the present urban environment where mobile, biogenic, and VCP VOCs are all important contributors to ozone formation.
AB - The declining trend in vehicle emissions has underscored the growing significance of volatile organic compound (VOC) emissions from volatile chemical products (VCPs). However, accurately representing VOC chemistry in simplified chemical mechanisms remains challenging due to its chemical complexity including speciation and reactivity. Previous studies have predominantly focused on VOCs from fossil fuel sources, leading to an underrepresentation of VOC chemistry from VCP sources. We developed an integrated chemical mechanism, RACM2B-VCP, that is compatible with WRF-Chem and is aimed at enhancing the representation of VOC chemistry, particularly from VCP sources, within the present urban environment. Evaluation against the Air Quality System (AQS) network data demonstrates that our model configured with RACM2B-VCP reproduces both the magnitude and spatial variability of O3 and PM2.5 in Los Angeles. Furthermore, evaluation against comprehensive measurements of O3 and PM2.5 precursors from the Reevaluating the Chemistry of Air Pollutants in California (RECAP-CA) airborne campaign and the Southwest Urban NOx and VOC Experiment (SUNVEx) ground site and mobile laboratory campaign confirm the model's accuracy in representing NOx and many VOCs and highlight remaining biases. Although there exists an underprediction in the total VOC reactivity of observed VOC species, our model with RACM2B-VCP exhibits good agreement for VOC markers emitted from different sectors, including biogenic, fossil fuel, and VCP sources. Through sensitivity analyses, we probe the contributions of VCP and fossil fuel emissions to total VOC reactivity and O3. Our results reveal that 52ĝ€¯% of the VOC reactivity and 35ĝ€¯% of the local enhancement of MDA8 O3 arise from anthropogenic VOC emissions in Los Angeles. Significantly, over 50ĝ€¯% of this anthropogenic fraction of either VOC reactivity or O3 is attributed to VCP emissions. The RACM2B-VCP mechanism created, described, and evaluated in this work is ideally suited for accurately representing ozone for the right reasons in the present urban environment where mobile, biogenic, and VCP VOCs are all important contributors to ozone formation.
UR - https://www.scopus.com/pages/publications/85193313840
U2 - 10.5194/acp-24-5265-2024
DO - 10.5194/acp-24-5265-2024
M3 - Article
AN - SCOPUS:85193313840
SN - 1680-7316
VL - 24
SP - 5265
EP - 5286
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
IS - 9
ER -