        dissipative_heat -- real, dimension(:,:,:)
             shape must conform to that of u, v, t, etc
	     units: deg_K/s 
	     
	     (computed when do_conserve_energy = .true.
	      and added to dt_t before temperature is diffused)

     optional input:

          kbot -- integer,dimension(:,:)
             shape must conform to first two dimensions of xi

             For use with models in which different columns
             have different number of levels above the surface.
             The le