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| Titel |
Signature of tropical fires in the diurnal cycle of tropospheric CO as seen from Metop-A/IASI |
| VerfasserIn |
T. Thonat, C. Crevoisier, N. A. Scott, A. Chédin, R. Armante, L. Crépeau |
| 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. 22 ; Nr. 15, no. 22 (2015-11-25), S.13041-13057 |
| Datensatznummer |
250120182
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| Publikation (Nr.) |
 copernicus.org/acp-15-13041-2015.pdf |
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| Zusammenfassung |
| Five years (July 2007 to June 2012) of CO tropospheric columns
derived from the hyperspectral Infrared Atmospheric Sounding Interferometer
(IASI) on-board Metop-A are used to study the impact of fires on the
concentrations of CO in the troposphere. Following Chédin et al. (2005,
2008), who found a quantitative relation between the daily tropospheric
excess of CO2 and fire emissions, we show that tropospheric CO also
displays a diurnal signal with a seasonality that agrees well with the
seasonal evolution of fires given by Global Fire Emission Database version 3
(GFED3.1) and Global Fire Assimilation System version 1 (GFAS1.0) emissions
and Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5
burned area product. Unlike day- or night-time CO fields, which mix local
emissions with nearby emissions transported to the region of study, the
day–night difference of CO allows to highlight the CO signal due to local
fire emissions. A linear relationship between CO fire emissions from the
GFED3.1 and GFAS1.0 inventories and the diurnal difference of IASI CO was
found over various regions in the tropics, with a better agreement with
GFAS1.0 (correlation coefficient of R2 ∼ 0.7) than
GFED3.1 (R2 ∼ 0.6). Based on the specificity of the two
main phases of the combustion (flaming vs. smoldering) and on the vertical
sensitivity of the sounder to CO, the following mechanism is proposed to
explain such a CO diurnal signal: at night, after the passing of IASI at
21:30 local time (LT), a large amount of CO emissions from the
smoldering phase is trapped in the boundary layer before being uplifted the
next morning by natural and pyroconvection up to the free troposphere,
where it is seen by IASI at 09:30 LT. The results presented here
highlight the need to take into account the specificity of both the
flaming and smoldering phases of fire emissions in order to fully take
advantage of CO observations. |
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