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| Titel |
Assessing the near surface sensitivity of SCIAMACHY atmospheric CO2 retrieved using (FSI) WFM-DOAS |
| VerfasserIn |
M. P. Barkley, P. S. Monks, A. J. Hewitt, T. Machida, A. Desai, N. Vinnichenko, T. Nakazawa, M. Yu Arshinov, N. Fedoseev, T. Watai |
| 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 ; 7, no. 13 ; Nr. 7, no. 13 (2007-07-09), S.3597-3619 |
| Datensatznummer |
250005127
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| Publikation (Nr.) |
 copernicus.org/acp-7-3597-2007.pdf |
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| Zusammenfassung |
Satellite observations of atmospheric CO2 offer
the potential to identify regional carbon surface sources and sinks
and to investigate carbon cycle processes. The extent to which
satellite measurements are useful however, depends on the near
surface sensitivity of the chosen sensor. In this paper, the
capability of the SCIAMACHY instrument on board ENVISAT, to observe
lower tropospheric and surface CO2 variability is examined.
To achieve this, atmospheric CO2 retrieved from SCIAMACHY
near infrared (NIR) spectral measurements, using the Full Spectral
Initiation (FSI) WFM-DOAS algorithm, is compared to in-situ aircraft
observations over Siberia and additionally to tower and surface
CO2 data over Mongolia, Europe and North America.
Preliminary validation of daily averaged SCIAMACHY/FSI CO2
against ground based Fourier Transform Spectrometer (FTS) column
measurements made at Park Falls, reveal a negative bias of about
−2.0% for collocated measurements within ±1.0° of the
site. However, at this spatial threshold SCIAMACHY can only capture
the variability of the FTS observations at monthly timescales. To
observe day to day variability of the FTS observations, the
collocation limits must be increased. Furthermore, comparisons to
in-situ CO2 observations demonstrate that SCIAMACHY is
capable of observing a seasonal signal that is representative of
lower tropospheric variability on (at least) monthly timescales. Out
of seventeen time series comparisons, eleven have correlation
coefficients of 0.7 or more, and have similar seasonal cycle
amplitudes. Additional evidence of the near surface sensitivity of
SCIAMACHY, is provided through the significant correlation of FSI
derived CO2 with MODIS vegetation indices at over twenty
selected locations in the United States. The SCIAMACHY/MODIS
comparison reveals that at many of the sites, the amount of
CO2 variability is coincident with the amount of vegetation
activity. The presented analysis suggests that SCIAMACHY has the
potential to detect CO2 variability within the lowermost
troposphere arising from the activity of the terrestrial biosphere. |
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