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| Titel |
Improving North American terrestrial CO2 flux diagnosis using spatial structure in land surface model residuals |
| VerfasserIn |
T. W. Hilton, K. J. Davis, K. Keller, N. M. Urban |
| 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 ; 10, no. 7 ; Nr. 10, no. 7 (2013-07-11), S.4607-4625 |
| Datensatznummer |
250018333
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| Publikation (Nr.) |
 copernicus.org/bg-10-4607-2013.pdf |
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| Zusammenfassung |
| We evaluate spatial structure in North American CO2 flux
observations using a simple diagnostic land surface model. The
vegetation photosynthesis respiration model (VPRM) calculates net
ecosystem exchange (NEE) using locally observed temperature and
photosynthetically active radiation (PAR) along with
satellite-derived phenology and moisture. We use observed NEE from
a group of 65 North American eddy covariance tower sites spanning
North America to estimate VPRM parameters for these sites. We
investigate spatial coherence in regional CO2 fluxes at
several different time scales by using geostatistical methods to
examine the spatial structure of model–data residuals. We
find that persistent spatial structure does exist in the model–data
residuals at a length scale of approximately 400 km (median
402 km, mean 712 km, standard deviation
931 km). This spatial structure defines a flux-tower-based
VPRM residual covariance matrix. The residual covariance matrix is
useful in constructing prior fluxes for atmospheric CO2
concentration inversion calculations, as well as for constructing
a VPRM North American CO2 flux map optimized to eddy
covariance observations. Finally (and secondarily), the estimated
VPRM parameter values do not separate clearly by plant functional
type (PFT). This calls into question whether PFTs can successfully
partition ecosystems' fundamental ecological drivers when the
viewing lens is a simple model. |
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