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| Titel |
Global upper-tropospheric formaldehyde: seasonal cycles observed by the ACE-FTS satellite instrument |
| VerfasserIn |
G. Dufour, S. Szopa, M. P. Barkley, C. D. Boone, A. Perrin, P. I. Palmer, P. F. Bernath |
| 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. 12 ; Nr. 9, no. 12 (2009-06-16), S.3893-3910 |
| Datensatznummer |
250007425
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| Publikation (Nr.) |
 copernicus.org/acp-9-3893-2009.pdf |
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| Zusammenfassung |
| Seasonally-resolved upper tropospheric profiles of formaldehyde (HCHO)
observed by the ACE Fourier transform spectrometer (ACE-FTS) on a
near-global scale are presented for the time period from March 2004 to
November 2006. Large upper tropospheric HCHO mixing ratios (>150 pptv)
are observed during the growing season of the terrestrial biosphere in the
Northern Hemisphere and during the biomass burning season in the Southern Hemisphere.
The total errors estimated for the retrieved mixing ratios range
from 30 to 40% in the upper troposphere and increase in the lower
stratosphere. The sampled HCHO concentrations are in satisfactory agreement
with previous aircraft and satellite observations with a negative bias
(<25%) within observation errors. An overview of the seasonal cycle of
the upper tropospheric HCHO is given for different latitudes, with a particular focus
on mid-to-high latitudes that are well sampled by the observations. A maximum is
observed during summer, i.e. during the growing season, in the northern mid-
and high latitudes. The influence of biomass burning is visible in HCHO
upper tropospheric concentrations during the September-to-October period in
the southern tropics and subtropics. Comparisons with two state-of-the-art
models (GEOS-Chem and LMDz-INCA) show that the models
capture well the seasonal variations observed in the Northern Hemisphere (correlation
>0.9). Both models underestimate the summer maximum over Europe and
Russia and differences in the emissions used for North America result in a
good reproduction of the summer maximum by GEOS-Chem but in an underestimate
by LMDz-INCA. Globally, GEOS-Chem reproduces well the observations on
average over one year but has some difficulties in reproducing the spatial
variability of the observations. LMDz-INCA shows significant bias in the
Southern Hemisphere, perhaps related to an underestimation of methane, but
better reproduces the temporal and spatial variations. The differences
between the models underline the large uncertainties that remain in the
emissions of HCHO precursors. |
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