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| Titel |
Global CO2 fluxes estimated from GOSAT retrievals of total column CO2 |
| VerfasserIn |
S. Basu, S. Guerlet, A. Butz, S. Houweling, O. Hasekamp, I. Aben, P. Krummel, P. Steele, R. Langenfelds, M. Torn, S. Biraud, B. Stephens, A. Andrews, D. Worthy |
| 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 ; 13, no. 17 ; Nr. 13, no. 17 (2013-09-03), S.8695-8717 |
| Datensatznummer |
250085666
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| Publikation (Nr.) |
 copernicus.org/acp-13-8695-2013.pdf |
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| Zusammenfassung |
| We present one of the first estimates of the global distribution of CO2
surface fluxes using total column CO2 measurements retrieved by the
SRON-KIT RemoTeC algorithm from the Greenhouse gases Observing SATellite
(GOSAT). We derive optimized fluxes from June 2009 to December 2010. We
estimate fluxes from surface CO2 measurements to use as baselines for
comparing GOSAT data-derived fluxes. Assimilating only GOSAT data, we can
reproduce the observed CO2 time series at surface and TCCON sites in the
tropics and the northern extra-tropics. In contrast, in the southern
extra-tropics GOSAT XCO2 leads to enhanced seasonal cycle amplitudes compared
to independent measurements, and we identify it as the result of a land–sea
bias in our GOSAT XCO2 retrievals. A bias correction in the form of a global
offset between GOSAT land and sea pixels in a joint inversion of satellite
and surface measurements of CO2 yields plausible global flux estimates
which are more tightly constrained than in an inversion using surface
CO2 data alone. We show that assimilating the bias-corrected GOSAT data
on top of surface CO2 data (a) reduces the estimated global land sink of
CO2, and (b) shifts the terrestrial net uptake of carbon from the
tropics to the extra-tropics. It is concluded that while GOSAT total column
CO2 provide useful constraints for source–sink inversions, small
spatiotemporal biases – beyond what can be detected using current validation
techniques – have serious consequences for optimized fluxes, even aggregated
over continental scales. |
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