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| Titel |
Multi-scale modeling study of the source contributions to near-surface ozone and sulfur oxides levels over California during the ARCTAS-CARB period |
| VerfasserIn |
M. Huang, G. R. Carmichael, S. N. Spak, B. Adhikary, S. Kulkarni, Y. Cheng, C. Wei, Y. Tang, A. D'Allura, P. O. Wennberg, G. L. Huey, J. E. Dibb, J. L. Jimenez, M. J. Cubison, A. J. Weinheimer, A. Kaduwela, C. Cai, M. Wong, R. Bradley Pierce, J. A. Al-Saadi, D. G. Streets, Q. Zhang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 7 ; Nr. 11, no. 7 (2011-04-04), S.3173-3194 |
| Datensatznummer |
250009586
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| Publikation (Nr.) |
 copernicus.org/acp-11-3173-2011.pdf |
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| Zusammenfassung |
| Chronic high surface ozone (O3) levels and the increasing sulfur oxides
(SOx = SO2+SO4) 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 O3 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
O3 levels. California biogenic and fire emissions contribute 3–4 ppb to
near-surface O3 over SC, with larger contributions to other regions in
CA. During a long-range transport event from Asia starting from 22 June,
high SOx levels (up to ~0.7 ppb of SO2 and ~1.3 ppb of
SO4) is observed above ~6 km, but they did not affect CA surface
air quality. The elevated SOx observed at 1–4 km is estimated to enhance
surface SOx over SC by ~0.25 ppb (upper limit) on ~24 June.
The near-surface SOx levels over SC during the flight week are
attributed mostly to local emissions. Two anthropogenic SOx 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 SOx by
about a factor of two. Adjoint sensitivity analysis indicated that SO2
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 SO2 from the north through
both terrestrial and maritime areas. Overall maritime emissions contribute
10–70% of SO2 and 20–60% fine SO4 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 O3 production over coastal SC to more VOC-limited conditions.
These suggest an important role for shipping emission controls in reducing
fine particle and O3 concentrations in SC. |
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