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| Titel |
Long-term analysis of carbon dioxide and methane column-averaged mole fractions retrieved from SCIAMACHY |
| VerfasserIn |
O. Schneising, M. Buchwitz, M. Reuter, J. Heymann, H. Bovensmann, J. P. Burrows |
| 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 ; 11, no. 6 ; Nr. 11, no. 6 (2011-03-28), S.2863-2880 |
| Datensatznummer |
250009526
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| Publikation (Nr.) |
 copernicus.org/acp-11-2863-2011.pdf |
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| Zusammenfassung |
Carbon dioxide (CO2) and methane (CH4) are the two
most important anthropogenic greenhouse gases contributing to global
climate change. SCIAMACHY onboard ENVISAT (launch 2002) was the first
and is now with TANSO onboard GOSAT (launch 2009) one of only two
satellite instruments currently in space whose measurements are
sensitive to CO2 and CH4 concentration changes in the
lowest atmospheric layers where the variability due to sources and
sinks is largest.
We present long-term SCIAMACHY retrievals (2003–2009) of column-averaged
dry air mole fractions of both gases (denoted XCO2 and
XCH4) derived from absorption bands in the
near-infrared/shortwave-infrared (NIR/SWIR) spectral region focusing
on large-scale features. The results are obtained using an upgraded
version (v2) of the retrieval algorithm WFM-DOAS including several
improvements, while simultaneously maintaining its high processing
speed. The retrieved mole fractions are compared to global model
simulations (CarbonTracker XCO2 and TM5 XCH4) being
optimised by assimilating highly accurate surface measurements from
the NOAA/ESRL network and taking the SCIAMACHY averaging kernels into
account. The comparisons address seasonal variations and long-term
characteristics.
The steady increase of atmospheric carbon dioxide primarily caused by
the burning of fossil fuels can be clearly observed with SCIAMACHY
globally. The retrieved global annual mean XCO2 increase agrees
with CarbonTracker within the error bars (1.80±0.13 ppm yr−1
compared to 1.81±0.09 ppm yr−1). The amplitude of
the XCO2 seasonal cycle as retrieved by SCIAMACHY, which is
4.3±0.2 ppm for the Northern Hemisphere and 1.4±0.2 ppm for
the Southern Hemisphere, is on average about 1 ppm larger than for
CarbonTracker.
An investigation of the boreal forest carbon uptake during the growing
season via the analysis of longitudinal gradients shows good agreement
between SCIAMACHY and CarbonTracker concerning the overall magnitude
of the gradients and their annual variations. The analysis includes a
discussion of the relative uptake strengths of the Russian and North
American boreal forest regions.
The retrieved XCH4 results show that after years of stability,
atmospheric methane has started to rise again in recent years which is
consistent with surface measurements. The largest increase is observed
for the tropics and northern mid- and high-latitudes amounting to about
7.5±1.5 ppb yr−1 since 2007. Due care has been exercised to
minimise the influence of detector degradation on the quantitative
estimate of this anomaly. |
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