We now explain how to set the parameters for an individual simulation in the subdirectory MAIN. There are two type of preparations for the simulation. Any changes made to the model code in the files ending in .f, .F, or .h (changing model physics such as wind stress, type of diffusion, partial cells, etc.) require that the program be recompiled with the MAIN/ Makefile. Any changes governing the model simulation (timestep, length of run, etc.) can be set in file Runtime_parm.tag (see below) that is read by the program at time of execution and therefore do not require compilation.