and that the pressure 
             thicknesses of the underground layers are non-zero as well.  
              
==========================================================================

subroutine gcm_vert_diff_up (is, js, delt, Tri_surf, dt_t, dt_q, kbot)

   input:

         is, js -- integers
             the location in the global lon-lat grid of the rectangular
             domain on which diffusion is to be performed
             the size of the domain is determined by the size ofthe input
        