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Title:
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Inverse carbon dioxide flux estimates for the Netherlands
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Author(s):
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Meesters, A.G.C.A. ; Tolk, L.F. ; Peters, W. ; Hutjes, R.W.A.; Vellinga, O.; Elbers, J.A.; Vermeulen, A.T.; Laan, S. van der; Neubert, R.E.M.; Meijer, H.A.J.; Dolman, A.J.
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Published by:
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Publication date:
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ECN
Environment & Energy Engineering
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29-10-2012
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ECN report number:
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Document type:
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ECN-W--12-047
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Article (scientific)
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Number of pages:
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13
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Published in: Journal of Geophysical Research (AGU), , 2012, Vol.Volume 117, p.-.
Abstract:
CO2 fluxes for the Netherlands and surroundings are estimated for the year 2008,
from concentration measurements at four towers, using an inverse model. The results
are compared to direct CO2 flux measurements by aircraft, for 6 flight tracks over the
Netherlands, flown multiple times in each season. We applied the Regional Atmospheric
Mesoscale Modeling system (RAMS) coupled to a simple carbon flux scheme (including
fossil fuel), which was run at 10 km resolution, and inverted with an Ensemble Kalman
Filter. The domain had 6 eco-regions, and inversions were performed for the four seasons
separately. Inversion methods with pixel-dependent and -independent parameters for
each eco-region were compared. The two inversion methods, in general, yield comparable
flux averages for each eco-region and season, whereas the difference from the prior flux
may be large. Posterior fluxes co-sampled along the aircraft flight tracks are usually much
closer to the observations than the priors, with a comparable performance for both inversion
methods, and with best performance for summer and autumn. The inversions showed
more negative CO2 fluxes than the priors, though the latter are obtained from a biosphere
model optimized using the Fluxnet database, containing observations from more than
200 locations worldwide. The two different crop ecotypes showed very different CO2
uptakes, which was unknown from the priors. The annual-average uptake is practically zero
for the grassland class and for one of the cropland classes, whereas the other cropland class
had a large net uptake, possibly because of the abundance of maize there.
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