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| Titel |
A regional high-resolution carbon flux inversion of North America for 2004 |
| VerfasserIn |
A. E. Schuh, A. S. Denning, K. D. Corbin, I. T. Baker, M. Uliasz, N. Parazoo, A. E. Andrews, D. E. J. Worthy |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 5 ; Nr. 7, no. 5 (2010-05-20), S.1625-1644 |
| Datensatznummer |
250004774
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| Publikation (Nr.) |
 copernicus.org/bg-7-1625-2010.pdf |
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| Zusammenfassung |
| Resolving the discrepancies between NEE estimates based upon (1) ground studies and (2)
atmospheric inversion results, demands increasingly sophisticated techniques. In this paper
we present a high-resolution inversion based upon a regional meteorology model (RAMS) and an
underlying biosphere (SiB3) model, both running on an identical 40 km grid over most
of North America. Current operational systems like CarbonTracker as well
as many previous global inversions including the Transcom suite of inversions have utilized inversion regions formed by collapsing
biome-similar grid cells into larger aggregated regions. An extreme example of this might be where corrections to NEE
imposed on forested regions on the east coast of the United States might
be the same as that imposed on forests on the west coast of the United States while, in
reality, there likely exist subtle differences in the two areas, both natural and
anthropogenic. Our current inversion framework utilizes a combination of previously employed
inversion techniques while allowing carbon flux corrections to be biome
independent. Temporally and spatially high-resolution results utilizing biome-independent
corrections provide insight into carbon dynamics in North America. In particular, we analyze
hourly CO2 mixing ratio data from a sparse network of eight towers in North
America for 2004. A prior estimate of carbon fluxes due to Gross Primary Productivity (GPP)
and Ecosystem Respiration (ER) is constructed from the SiB3 biosphere model on
a 40 km grid. A combination of transport from the RAMS and the Parameterized
Chemical Transport Model (PCTM) models is used to forge a connection between upwind
biosphere fluxes and downwind observed CO2 mixing ratio data. A Kalman filter
procedure is used to estimate weekly corrections to biosphere fluxes based upon observed
CO2. RMSE-weighted annual NEE estimates, over an ensemble of potential inversion
parameter sets, show a mean estimate 0.57 Pg/yr sink in North America. We perform
the inversion with two independently derived boundary inflow conditions and calculate
jackknife-based statistics to test the robustness of the model results. We then compare
final results to estimates obtained from the CarbonTracker inversion system and at the
Southern Great Plains flux site. Results are promising, showing the ability to correct carbon fluxes from
the biosphere models over annual and seasonal time scales, as well as over the different GPP
and ER components. Additionally, the correlation of an estimated sink
of carbon in the South Central United States with regional anomalously high precipitation
in an area of managed agricultural and forest lands provides interesting hypotheses for future work. |
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