Jan Polcher

Patricia de Rosnay

Laboratoire de Météorologie Dynamique du CNRS
Tour 25, 5ème étage, Case 99,
4 pl. Jussieu,
75252 PARIS cedex 05
Phone : -33-1-44274763,
FAX : -33-1-44276272,
E-mail : Jan.Polcher@lmd.jussieu.fr

Jan Polcher has obtained his Doctorate Degree from the Université Pierre et Marie Curie (Paris, France) and is now Chargé de Recherche at the CNRS. His main topics of research is modelling land-surfaces in general circulation models and the study of the sensitivity of climate to land-surface processes. Current activities include the coordination of the development of the SECHIBA land-surface scheme which was originally formulated at the Laboratoire de Météorologie Dynamique du CNRS. In progress is the analysis of GCM experiments which aim at quantifying the impact of surface processes on inter-annual climate variability and the uncertainty in climate change predictions.

Patricia de Rosnay has incorporated into SECHIBA an improved parametrization of the extraction of water from soils by root and replaced the simple hydrology by a multilayer scheme with a sufficient vertical resolution in the top 5 cm to allow for a good modeling of the L-bande radiative temperature.

Polcher, J., (1995) Sensitivity of tropical convection to land surface processes., Journal of the Atmospheric Sciences, 52, 17, 3143-3161

Peylin, P., Polcher, J., Bonan, G., Williamson, D. and Laval, K. (1997) Comparison of two complex Land-surface schemes coupled to the NCAR-GCM, J.G.R., 102,19,413-19,431.

Polcher, J., McAvaney, B., Viterbo, P., Gaertner, M.-A., Hahmann, A., Mahfouf, J.-F., Noilhan, J., Phillips, T., Pitman, A., Schlosser, C.A., Schulz, J.-P., Timbal, B., Verseghy, D. and Xue Y. (1998) A proposal for a general interface between land-surface schemes and general circulation models. Global and Planetary Change,19, 263-278

Polcher, J, J. Crossley, C. Bunton, H. Douville, N. Gedney, K. Laval, S. Planton, P.R. Rowntree, and P. Valdes (1998) Importance of land-surface processes for the uncertainties of climate change; A European project GEWEX News, May.

De Rosnay, P. and Polcher, J. (1998) Improvements of the representation of the hydrological exchanges between the biosphere and the atmosphere in a GCM. Hydrology and Earth System Sciences, 2,


Role in the SMOS mission:

The LMD will assimilate the observed L-band radiances in its land-surface scheme and produce climatologies of hydrological parameters. The originality of this contribution lies in the fact that SECHIBA explicitly takes into account the sub-grid variability of surface conditions and includes an advanced hydrological component. The data and expertise obtained through this project will then be used for climate change and climate variability studies with the LMD general circulation model.