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| Titel |
Injection in the lower stratosphere of biomass fire emissions followed by long-range transport: a MOZAIC case study |
| VerfasserIn |
J.-P. Cammas, J. Brioude, J.-P. Chaboureau, J. Duron, C. Mari, P. Mascart, P. Nédélec, H. Smit, H.-W. Pätz, A. Volz-Thomas, A. Stohl, M. Fromm |
| 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 ; 9, no. 15 ; Nr. 9, no. 15 (2009-08-12), S.5829-5846 |
| Datensatznummer |
250007572
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| Publikation (Nr.) |
 copernicus.org/acp-9-5829-2009.pdf |
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| Zusammenfassung |
| This paper analyses a stratospheric injection by deep convection of
biomass fire emissions over North America (Alaska, Yukon and Northwest
Territories) on 24 June 2004 and its long-range transport over the
eastern coast of the United States and the eastern Atlantic. The case study
is based on airborne MOZAIC observations of ozone, carbon monoxide, nitrogen
oxides and water vapour during the crossing of the southernmost tip of an
upper level trough over the Eastern Atlantic on 30 June and on a vertical
profile over Washington DC on 30 June, and on lidar observations of
aerosol backscattering at Madison (University of Wisconsin) on 28 June.
Attribution of the observed CO plumes to the boreal fires is achieved by backward
simulations with a Lagrangian particle dispersion model (FLEXPART). A simulation
with the Meso-NH model for the source region shows that a boundary layer tracer,
mimicking the boreal forest fire smoke, is lofted into the lowermost stratosphere
(2–5 pvu layer) during the diurnal convective cycle at isentropic levels (above
335 K) corresponding to those of the downstream MOZAIC observations. It is shown
that the order of magnitude of the time needed by the parameterized convective
detrainment flux to fill the volume of a model mesh (20 km horizontal, 500 m
vertical) above the tropopause with pure boundary layer air would be about 7.5 h,
i.e. a time period compatible with the convective diurnal cycle. Over the area of
interest, the maximum instantaneous detrainment fluxes deposited about 15 to
20% of the initial boundary layer tracer concentration at 335 K. According to the
275-ppbv carbon monoxide maximum mixing ratio observed by MOZAIC over Eastern
Atlantic, such detrainment fluxes would be associated with a 1.4–1.8 ppmv
carbon monoxide mixing ratio in the boundary layer over the source region. |
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