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| Titel |
An attempt at estimating Paris area CO2 emissions from atmospheric concentration measurements |
| VerfasserIn |
F. M. Bréon, G. Broquet, V. Puygrenier, F. Chevallier, I. Xueref-Remy, M. Ramonet, E. Dieudonné, M. López, M. Schmidt, O. Perrussel, P. Ciais |
| 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 ; 15, no. 4 ; Nr. 15, no. 4 (2015-02-18), S.1707-1724 |
| Datensatznummer |
250119440
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| Publikation (Nr.) |
 copernicus.org/acp-15-1707-2015.pdf |
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| Zusammenfassung |
Atmospheric concentration measurements are used to adjust the daily to monthly budget of
fossil fuel CO2 emissions of the Paris urban area from the prior
estimates established by the Airparif local air quality agency. Five
atmospheric monitoring sites are available, including one at the top of the
Eiffel Tower. The atmospheric inversion is based on a Bayesian approach, and
relies on an atmospheric transport model with a spatial resolution of 2 km
with boundary conditions from a global coarse grid transport model. The
inversion adjusts prior knowledge about the anthropogenic and biogenic
CO2 fluxes from the Airparif inventory and an ecosystem model,
respectively, with corrections at a temporal resolution of 6 h, while
keeping the spatial distribution from the emission inventory. These
corrections are based on assumptions regarding the temporal autocorrelation
of prior emissions uncertainties within the daily cycle, and from day to day.
The comparison of the measurements against the atmospheric transport
simulation driven by the a priori CO2 surface fluxes shows significant
differences upwind of the Paris urban area, which suggests a large and
uncertain contribution from distant sources and sinks to the CO2
concentration variability. This contribution advocates that the inversion
should aim at minimising model–data misfits in upwind–downwind gradients
rather than misfits in mole fractions at individual sites. Another conclusion
of the direct model–measurement comparison is that the CO2 variability
at the top of the Eiffel Tower is large and poorly represented by the model
for most wind speeds and directions. The model's inability to reproduce the
CO2 variability at the heart of the city makes such measurements
ill-suited for the inversion. This and the need to constrain the budgets for
the whole city suggests the assimilation of upwind–downwind mole fraction
gradients between sites at the edge of the urban area only.
The inversion significantly improves the agreement between measured and
modelled concentration gradients. Realistic emissions are retrieved for two
30-day periods and suggest a significant overestimate by the AirParif
inventory. Similar inversions over longer periods are necessary for a proper
evaluation of the optimised CO2 emissions against independent data. |
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