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

The Simplified SiB (SSiB) model (Xue et al., 1991, 1996) is used 
to model the land surface in the GCM and regional model.  SSiB has three 
soil layers, one canopy layer, and eight prognostic variables: volumetric 
soil moisture content in three soil layers; temperature at the canopy, 
ground surface and deep soil layers; water stored on the canopy; and snow 
stored on the ground.

In the three layer soil model, water movement is described by a finite
-difference approximation to the diffusion equation.  The force-restore 
method is used to predict the time variation of soil temperature.  The 
governing equations for the interception water stores are based on water 
conservation equations.

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

Xue, Y., P. J. Sellers, J.L. Kinter III, and J. Shukla, 1991: A Simplified 
Bios phere Model for Global Climate Studies.  J. Climate, 4, 345-364.

Xue, Y., P.J. Sellers, F.J. Zeng, and C.A. Schlosser, 1997: Comments on 
"Use of midlatitude soil moisture and meteorological observations to 
validate soil moisture sim ulations with biosphere and bucket models".  
J. Climate, 10, 374-376.

Schlosser, C.A., A. Robock, K.Y. Vinnikov, N.A. Speranskaya, and Y. Xue, 
1996: 18-year land- surface hydrology model simulations for a midlatitude 
grassland catchment in Valdai, Russia.  Submitted to Mon. Wea. Rev., 
accepted.