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The inter-annual variability of Africa's ecosystem productivity: a multi-model analysis
U. Weber1,2, M. Jung2, M. Reichstein2, C. Beer2, M. Braakhekke2, V. Lehsten3, D. Ghent4, J. Kaduk4, N. Viovy5, P. Ciais5, N. Gobron6, and C. Rödenbeck2
1Department of Forest Science and Environment,University of Tuscia, Viterbo, Italy
2Max Planck Institute for Biogeochemistry, Jena, Germany
3GeoBiosphere Science Centre, Lund University, Sweden
4Department of Geography, University of Leicester, UK
5Laboratoire des Sciences du Climate et de l' Environnement, Gif-sur-Yvette, France
6European Commission – DG Joint Research Centre, Institute for Environment and Sustainability, Global Environment Monitoring Unit, Ispra (VA), Italy
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Abstract. We are comparing spatially explicit process-model based estimates of the
terrestrial carbon balance and its components over Africa and confront them
with remote sensing based proxies of vegetation productivity and atmospheric
inversions of land-atmosphere net carbon exchange. Particular emphasis is on
characterizing the patterns of interannual variability of carbon fluxes and
analyzing the factors and processes responsible for it. For this purpose
simulations with the terrestrial biosphere models ORCHIDEE, LPJ-DGVM,
LPJ-Guess and JULES have been performed using a standardized modeling
protocol and a uniform set of corrected climate forcing data. While the
models differ concerning the absolute magnitude of carbon fluxes, we find
several robust patterns of interannual variability among the models. Models
exhibit largest interannual variability in southern and eastern Africa,
regions which are primarily covered by herbaceous vegetation. Interannual
variability of the net carbon balance appears to be more strongly influenced
by gross primary production than by ecosystem respiration. A principal
component analysis indicates that moisture is the main driving factor of
interannual gross primary production variability for those regions. On the
contrary in a large part of the inner tropics radiation appears to be
limiting in two models. These patterns are corroborated by remotely sensed
vegetation properties from the SeaWiFS satellite sensor. Inverse atmospheric
modeling estimates of surface carbon fluxes are less conclusive at this
point, implying the need for a denser network of observation stations over
Africa.
Discussion Paper (PDF, 4374 KB) Interactive Discussion (Closed, 4 Comments) Final Revised Paper (BG)
Citation: Weber, U., Jung, M., Reichstein, M., Beer, C., Braakhekke, M., Lehsten, V., Ghent, D., Kaduk, J., Viovy, N., Ciais, P., Gobron, N., and Rödenbeck, C.: The inter-annual variability of Africa's ecosystem productivity: a multi-model analysis, Biogeosciences Discuss., 5, 4035-4069, 2008. Bibtex EndNote Reference Manager
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