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| Titel |
A regional scale modeling analysis of aerosol and trace gas distributions over the eastern Pacific during the INTEX-B field campaign |
| VerfasserIn |
B. Adhikary, G. R. Carmichael, S. Kulkarni, C. Wei, Y. Tang, A. D'Allura, M. Mena-Carrasco, D. G. Streets, Q. Zhang, R. B. Pierce, J. A. Al-Saadi, L. K. Emmons, G. G. Pfister, M. A. Avery, J. D. Barrick, D. R. Blake, W. H. Brune, R. C. Cohen, J. E. Dibb, A. Fried, B. G. Heikes, L. G. Huey, D. W. O'Sullivan, G. W. Sachse, R. E. Shetter, H. B. Singh, T. L. Campos, C. A. Cantrell, F. M. Flocke, E. J. Dunlea, J. L. Jimenez, A. J. Weinheimer, J. D. Crounse, P. O. Wennberg, J. J. Schauer, E. A. Stone, D. A. Jaffe, D. R. Reidmiller |
| 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 ; 10, no. 5 ; Nr. 10, no. 5 (2010-03-01), S.2091-2115 |
| Datensatznummer |
250008158
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| Publikation (Nr.) |
 copernicus.org/acp-10-2091-2010.pdf |
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| Zusammenfassung |
| The Sulfur Transport and dEposition Model (STEM) is applied to the analysis
of observations obtained during the Intercontinental Chemical Transport
Experiment-Phase B (INTEX-B), conducted over the eastern Pacific Ocean
during spring 2006. Predicted trace gas and aerosol distributions over the
Pacific are presented and discussed in terms of transport and source region
contributions. Trace species distributions show a strong west (high) to east
(low) gradient, with the bulk of the pollutant transport over the central
Pacific occurring between ~20° N and 50° N in the 2–6 km
altitude range. These distributions are evaluated in the eastern Pacific by
comparison with the NASA DC-8 and NSF/NCAR C-130 airborne measurements
along with observations from the Mt. Bachelor (MBO) surface site. Thirty
different meteorological, trace gas and aerosol parameters are compared. In
general the meteorological fields are better predicted than gas phase
species, which in turn are better predicted than aerosol quantities. PAN is
found to be significantly overpredicted over the eastern Pacific, which is
attributed to uncertainties in the chemical reaction mechanisms used in
current atmospheric chemistry models in general and to the specifically high
PAN production in the SAPRC-99 mechanism used in the regional model. A
systematic underprediction of the elevated sulfate layer in the eastern
Pacific observed by the C-130 is another issue that is identified and
discussed. Results from source region tagged CO simulations are used to
estimate how the different source regions around the Pacific contribute to
the trace gas species distributions. During this period the largest
contributions were from China and from fires in South/Southeast and North
Asia. For the C-130 flights, which operated off the coast of the Northwest
US, the regional CO contributions range as follows: China (35%),
South/Southeast Asia fires (35%), North America anthropogenic (20%),
and North Asia fires (10%). The transport of pollution into the western
US is studied at MBO and a variety of events with elevated Asian dust, and
periods with contributions from China and fires from both Asia and North
America are discussed. The role of heterogeneous chemistry on the
composition over the eastern Pacific is also studied. The impacts of
heterogeneous reactions at specific times can be significant, increasing
sulfate and nitrate aerosol production and reducing gas phase nitric acid
levels appreciably (~50%). |
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