Huang, M. and Carmichael, G. R. and Spak, S. N. and Adhikary, B. and Kulkarni, S. and Cheng, Y. and Wei, C. and Tang, Y. and D'Allura, A. and Wennberg, P. O. and Huey, G. L. and Dibb, J. E. and Jimenez, J. L. and Cubison, M. J. and Weinheimer, A. J. and Kaduwela, A. and Cai, C. and Wong, M. and Pierce, R. Bradley and Al-Saadi, J. A. and Streets, D. G. and Zhang, Q. (2011) Multi-scale modeling study of the source contributions to near-surface ozone and sulfur oxides levels over California during the ARCTAS-CARB period. Atmospheric Chemistry and Physics, 11 (7). pp. 3173-3194. ISSN 1680-7316 http://resolver.caltech.edu/CaltechAUTHORS:20110624-134538082
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Chronic high surface ozone (O_3) levels and the increasing sulfur oxides (SO_x = SO_2 + SO_4) ambient concentrations over South Coast (SC) and other areas of California (CA) are affected by both local emissions and long-range transport. In this paper, multi-scale tracer, full-chemistry and adjoint simulations using the STEM atmospheric chemistry model are conducted to assess the contribution of local emission sourcesto SC O_3 and to evaluate the impacts of transported sulfur and local emissions on the SC sulfur budgetduring the ARCTAS-CARB experiment period in 2008. Sensitivity simulations quantify contributions of biogenic and fire emissions to SC O_3 levels. California biogenic and fire emissions contribute 3–4 ppb to near-surface O_3 over SC, with larger contributions to other regions in CA. During a long-range transport event from Asia starting from 22 June, high SO_x levels (up to ~0.7 ppb of SO_2 and ~1.3 ppb of SO_4) is observed above ~6 km, but they did not affect CA surface air quality. The elevated SO_x observed at 1–4 km is estimated to enhance surface SO_x over SC by ~0.25 ppb (upper limit) on ~24 June. The near-surface SO_x levels over SC during the flight week are attributed mostly to local emissions. Two anthropogenic SO_x emission inventories (EIs) from the California Air Resources Board (CARB) and the US Environmental Protection Agency (EPA) are compared and applied in 60 km and 12 km chemical transport simulations, and the results are compared withobservations. The CARB EI shows improvements over the National Emission Inventory (NEI) by EPA, but generally underestimates surface SC SO_x by about a factor of two. Adjoint sensitivity analysis indicated that SO_2 levels at 00:00 UTC (17:00 local time) at six SC surface sites were influenced by previous day maritime emissions over the ocean, the terrestrial emissions over nearby urban areas, and by transported SO_2 from the north through both terrestrial and maritime areas. Overall maritime emissions contribute 10–70% of SO2 and 20–60% fine SO_4 on-shore and over the most terrestrial areas, with contributions decreasing with in-land distance from the coast. Maritime emissions also modify the photochemical environment, shifting O_3 production over coastal SC to more VOC-limited conditions. These suggest an important role for shipping emission controls in reducing fine particle and O_3 concentrations in SC.
|Additional Information:||© Author(s) 2011. Published by Copernicus Publications on behalf of the European Geosciences Union. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 22 October 2010; Published in Atmos. Chem. Phys. Discuss.: 12 November 2010; Revised: 7 March 2011; Accepted: 27 March 2011; Published: 4 April 2011. We would like to thank the ARCTAS science team and two anonymous reviewers. We thank Tianfeng Chai (NOAA/OAR/ARL) for helping with the STEM adjoint model. This work was supported by a NASA award (NNX08AH56G). Jose L. Jimenez and Michael J. Cubisonwere supported by NASA NNX08AD39G. The authors would also like to acknowledge NOAA, the US EPA and CARB for support of the ground measurements. The views, opinions, and findings contained in this report are those of the author(s) and should not be construed as an official NOAA or US Government position, policy, or decision.|
|Official Citation:||Huang, M., Carmichael, G. R., Spak, S. N., Adhikary, B., Kulkarni, S., Cheng, Y., Wei, C., Tang, Y., D'Allura, A., Wennberg, P. O., Huey, G. L., Dibb, J. E., Jimenez, J. L., Cubison, M. J., Weinheimer, A. J., Kaduwela, A., Cai, C., Wong, M., Bradley Pierce, R., Al-Saadi, J. A., Streets, D. G., and Zhang, Q.: Multi-scale modeling study of the source contributions to near-surface ozone and sulfur oxides levels over California during the ARCTAS-CARB period, Atmos. Chem. Phys., 11, 3173-3194, doi:10.5194/acp-11-3173-2011, 2011.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||27 Jun 2011 14:46|
|Last Modified:||26 Dec 2012 13:20|
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