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| Titel |
Error characterization of SCIAMACHY WFM-DOAS XCO2: Impact of aerosols and cirrus clouds |
| VerfasserIn |
Jens Heymann, Oliver Schneising, Maximilian Reuter, Michael Buchwitz, Vladimir V. Rozanov, Heinrich Bovensmann, John P. Burrows |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250045719
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| Zusammenfassung |
| Carbon Dioxide (CO2) is the most important anthropogenic greenhouse gas. Column-averaged
dry air mole fractions of CO2 (XCO2) as retrieved from SCIAMACHY on-board
ENVISAT have the potential to provide important missing global information on
regional CO2 surface fluxes. This however requires to satisfy challenging accuracy
requirements. An important error source is scattering by aerosols and undetected clouds,
especially subvisual cirrus clouds. We have analyzed three years (2003 - 2005) of
SCIAMACHY XCO2 retrievals obtained with version 1.0 of the WFM-DOAS retrieval
algorithm (WFMDv1.0) with respect to errors caused by aerosols and cirrus clouds. As
reference, we use output of NOAA’s global CO2 assimilation and modeling system
CarbonTracker. In a first analysis step, it has been investigated to what extent SCIAMACHY
minus CarbonTracker XCO2 differences are spatially and temporally correlated
with global aerosol and cirrus clouds data sets. For this purpose, we have used a
global aerosol data set (2003 - 2005) generated within the European GEMS project,
which is based on assimilated MODIS satellite data. For cirrus clouds, we used a
one year data set (2007) derived from CALIPSO/CALIOP. We found significant
temporal correlations with cirrus clouds but also with aerosols. In a second step,
we generated simulated spectra using GEMS aerosol and CALIPSO cloud data
as input parameters for radiative transfer simulations and performed retrievals to
study to what extent the observed differences with respect to CarbonTracker can be
reproduced. We found that unaccounted variability of aerosols and cirrus clouds
can explain a significant fraction of the difference between SCIAMACHY and
CarbonTracker XCO2, in particular over the Southern Hemisphere. In addition, we present
first results of the application of a WFM-DOAS scattering correction algorithm. |
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