ine updates the tendencies of all fields

     If the dependence of the surface heat flux and evaporation
       on surface temperature is treated implicitly, then interfaces 
       are provided for dividing the up and down sweeps of the 
       standard tridiagonal elimination into two parts.  One can 
       visualize this procedure as starting with a downward 
       sweep through the atmosphere, which continue through the 
       surface, then re-emerges and continues up the atmosphere.
       A sample