If $RUNTYPE is set to startup, the model will read in the restart file that resides in $CSIMDATA called iced.0001-01-01.$ICE_GRID.20lay. The conditions in this file are for the gx1v3 grid and are from an equilibrium run using modified NCEP forcing. The setup script will create a pointer file named rpointer.ice with the name of the initial restart file in it Startup runs can also be initialized using data created within the ice model, as described in the next section.
Initial conditions can be calculated within the ice model in a subroutine called init_state in ice_init.F. Here, the ocean surface is initialized at the freezing point everywhere north of 40 degrees and south of -40 degrees latitude, allowing ice to form everywhere in these regions. While running the ice model with a data ocean will melt any extra ice during the first year of integration, is not recommended that these initial conditions be used when running the ice model coupled to an active ocean model. The advantage of using this input is that it is not grid or land mask dependent. To use these initial conditions, set $RESTART in csim.setup.csh:
set RESTART = .false.
Initializing the model using a restart file from an equilibrium run will result in a more physically reasonable scenario than the initial conditions set within CSIM. The drawbacks are that the data is binary, difficult to edit, and is date and grid dependent. A restart file will be used as initial conditions if
set RESTART = .true.
in csim.setup.csh.