ice_model_init
              .
     +->      .
     |  ice_bottom_to_ice_top
     |  +->   .
     |  |     .
     |  |  update_atmos_model_down
     |  |     .
     |  |     .
     |  |  update_ice_model_fast
     |  |     .
     |  |     .
     |  +--update_atmos_model_up
     |        .
     |        .
     |  update_ice_model_slow
     +--update_ocean_model
              .
              .
     ice_model_end

     FIGURE 1:  FMS DRIVER SCHEME