Agronomie 24 (2004) 397-407
DOI: 10.1051/agro:2004038

Coupling the Soil-Vegetation-Atmosphere-Transfer Scheme ORCHIDEE to the agronomy model STICS to study the influence of croplands on the European carbon and water budgets

Nathalie de Noblet-Ducoudré^a, Sébastien Gervois^a, Philippe Ciais^a, Nicolas Viovy^a, Nadine Brisson^b, Bernard Seguin^b and Alain Perrier<sup>c

a</sup>  Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Bât. 701, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France
^b  Institut National de Recherche Agronomique (INRA), Unité Climat, Sol et Environnement, Domaine St Paul, Site Agroparc, 84914 Avignon Cedex 9, France
^c  INAPG, Chaire de Bioclimatologie, Département AGER, 16 rue Claude Bernard, 75231 Paris Cedex 05, France

(Received 16 June 2003; accepted 14 May 2004)

Abstract - Agriculture is still accounted for in a very simplistic way in the land-surface models which are coupled to climate models, while the area it occupies will significantly increase in the next century according to future scenarios. In order to improve the representation of croplands in a Dynamic Global Vegetation Model named ORCHIDEE (which can be coupled to the IPSL¹ climate model), we have (1) developed a procedure which assimilates some of the variables simulated by a detailed crop model, STICS, and (2) modified some parameterisations to avoid inconsistencies between assimilated and computed variables in ORCHIDEE. Site simulations show that the seasonality of the cropland-atmosphere fluxes of water, energy and CO₂ is strongly modified when more realistic crop parameterisations are introduced in ORCHIDEE. A more realistic representation of wheat and corn croplands over Western Europe leads to a drying out of the atmosphere at the end of summer and during autumn, while the soils remain wetter, specially at the time when winter crops are sowed. The seasonality of net CO₂ uptake fluxes is also enhanced and shortened.

Key words: global biosphere modelling / heat and water fluxes / water balance / carbon balance / phenology

Corresponding author: Nathalie de Noblet-Ducoudré noblet@lsce.saclay.cea.fr

© INRA, EDP Sciences 2004