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| Titel |
Methane and carbon dioxide column-averaged mixing ratios from SCIAMACHY on ENVISAT |
| VerfasserIn |
M. Buchwitz, O. Schneising, M. Reuter, H. Bovensmann, J. P. Burrows |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022838
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| Zusammenfassung |
| Methane (CH4) and carbon dioxide (CO2) are the two most important
anthropogenic greenhouse gases and contribute to global
climate change. The spectral measurements of reflected and backscattered
solar radiation in the near-infrared spectral region of the SCIAMACHY
instrument onboard ENVISAT enable the retrieval of column-averaged
mixing ratios of both gases with high sensitivity for concentration
changes near the Earth's surface where the source/sink signals are largest.
At the University of Bremen the scientific algorithm WFM-DOAS has been
developed to retrieve this information from the measured spectra.
Several years of global data have been processed until
now (focus: 2003-2005) using the latest version of WFM-DOAS (version 1.0).
The analysis of the resulting greenhouse gas data sets
is an ongoing activity. For CO2 detailed comparisons have been performed with
the global CO2 fields of NOAA's CO2 assimilation system CarbonTracker.
Overall, reasonable to good agreement has been found but also interesting
differences. For example, the satellite retrievals show an amplitude of the
seasonal cycle of the colunm-averaged CO2 mixing ratio over the northern
hemisphere, which is significantly (about 40 percent) larger compared
to CarbonTracker. This may be due to still to be resolved retrieval issues
but this may also indicate that CarbonTracker (as well as other models)
significantly underestimates the seasonal amplitude of
the northern hemispheric terrestrial carbon fluxes.
Also for methane, the analysis of the existing data set is an ongoing activity.
Recently the methane data have been reprocessed to
assess the impact of newly available spectroscopic input parameters.
Initial analysis confirms the findings of Frankenberg et al., 2008, of
previously overestimated tropical methane due to interference with water vapor
absorption lines. In the presentation an overview about the current status of
the greenhouse gas retrievals from SCIAMACHY spectra will
be given. |
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