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| Titel |
Regional data assimilation of multi-spectral MOPITT observations of CO over North America |
| VerfasserIn |
Z. Jiang, D. B. A. Jones, J. Worden, H. M. Worden, D. K. Henze, Y. X. Wang |
| 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 ; 15, no. 12 ; Nr. 15, no. 12 (2015-06-19), S.6801-6814 |
| Datensatznummer |
250119841
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| Publikation (Nr.) |
 copernicus.org/acp-15-6801-2015.pdf |
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| Zusammenfassung |
| Chemical transport models (CTMs) driven with high-resolution meteorological
fields can better resolve small-scale processes, such as frontal lifting or
deep convection, and thus improve the simulation and emission estimates of
tropospheric trace gases. In this work, we explore the use of the GEOS-Chem
four-dimensional variational (4D-Var) data assimilation system with the
nested high-resolution version of the model
(0.5° × 0.67°) to quantify North American CO
emissions during the period of June 2004–May 2005. With optimized lateral
boundary conditions, regional inversion analyses can reduce the sensitivity
of the CO source estimates to errors in long-range transport and in the
distributions of the hydroxyl radical (OH), the main sink for CO. To further
limit the potential impact of discrepancies in chemical aging of air in the
free troposphere, associated with errors in OH, we use surface-level
multispectral MOPITT (Measurement of Pollution in The
Troposphere) CO retrievals, which have greater sensitivity to CO near
the surface and reduced sensitivity in the free troposphere, compared to
previous versions of the retrievals. We estimate that the annual total
anthropogenic CO emission from the contiguous US 48 states was 97 Tg CO, a
14 % increase from the 85 Tg CO in the a priori. This increase is
mainly due to enhanced emissions around the Great Lakes region and along the
west coast, relative to the a priori. Sensitivity analyses using different OH
fields and lateral boundary conditions suggest a possible error, associated
with local North American OH distribution, in these emission estimates of
20 % during summer 2004, when the CO lifetime is short. This 20 %
OH-related error is 50 % smaller than the OH-related error previously
estimated for North American CO emissions using a global inversion analysis.
We believe that reducing this OH-related error further will require
integrating additional observations to provide a strong constraint on the CO
distribution across the domain. Despite these limitations, our results show
the potential advantages of combining high-resolution regional inversion
analyses with global analyses to better quantify regional CO source
estimates. |
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