6. One paragraph description of your model (e.g. abstract from report or
   paper);

A simple physically-based snow hydrology has been developped at
M\'et\'eo-France for use in climate or NWP models, together with the
ISBA land-surface scheme. A restricted number of parameters has been
added, while preserving a single surface energy budget. The aging
process of the snow pack has been introduced through prognostic
equations for snow density and snow albedo. Snowmelt computation has
been modified over partially snow-covered and vegetated areas. The new
scheme has been validated against field measurements in stand-alone
simulations forced by observed meteorological conditions. The results
show a strong improvement in the model's performance, thereby suggesting
that a simple one-layer snow model is able to reproduce the main
physical mechanisms governing the snow pack evolution.

A global and coupled validation of the parameterization has been also
achieved through a 3-year integration for the present-day climate
within the T42L30 version of ARPEGE. Results are compared with those
from a control simulation and with available observed climatologies,
in order to assess the impact of the new snow parameterization on the
simulated surface climate. The seasonal cycle of the Northern
hemisphere snow cover is clearly improved when using the new scheme.
The snow pack is still slightly overestimated in winter, but its
poleward retreat is better reproduced during the melting season. As a
consequence, the modified GCM performs well in simulating the springtime
continental heating, which also improves some features of the general
atmospheric circulation (over Europe in spring or South Asia in summer).

50. Please provide references relevant to the model description and use.

Douville H, Royer JF, Mahfouf JF (1995a) A new snow parameterization for
the M\'et\'eo-France climate model, Part I :  Validation in stand-alone
experiments.  Climate Dyn 12:21-35

Douville H, Royer JF, Mahfouf JF (1995b) A new snow parameterization for
the M\'et\'eo-France climate model, Part II :  Validation Validation in
a 3D GCM experiment.  Climate Dyn 12:37-52

Douville H. and J-F. Royer (1996) :  Sensitivity of the Asian summer
monsoon to an anomalous Eurasian snow cover within the METEO-FRANCE
GCM, Climate Dyn., 12, 441-448.

Douville H. and J-F. Royer (1997a) :  Influence of the temperate and
boreal forests on the Northern Hemisphere climate in the METEO-FRANCE
climate model, Climate Dyn., 13:57-74.

Douville H.  (1997b) :  Local and global stand-alone tests of the
M\'et\'eo-France snow parameterization, Annals of Glaciology, 25 (in press)

Douville H.  (1997c) :  Validation and sensitivity of the global
hydrologic budget in stand-alone simulations with the ISBA land-surface
scheme, Climate Dynamics (in press)

        ============================================
                      Herve DOUVILLE
                Meteo-France CNRM/GMGEC/UDC
                42, avenue Gaspard Coriolis
               31057 Toulouse Cedex 1 FRANCE
                Phone : (33) 05 61 07 96 25
                Fax   : (33) 05 61 07 96 10
              Email  : Herve.Douville@meteo.fr
          http://www.meteo.fr/perso/herve.douville
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