 fms_mod
     field_manager_mod
     tracer_manager_mod

</PRE>
</A><!-- END MODULES_USED -->
<!--------------------------------------------------------------------->
<A NAME="INTERFACE">
<HR>
<H4>PUBLIC INTERFACE</H4>
<!-- BEGIN INTERFACE -->
<PRE>

  use vert_diff_mod [,only: gcm_vert_diff_init       , &
                            gcm_vert_diff_end        , &
                            vert_diff                , &
                            gcm_vert_diff            , &
                            gcm_v