When running the model as part of the CAM executable, CAM build and run scripts must be utilized and the user should refer to the CAM User's Guide for specific details on building and running the CAM executable. We will only discuss some essential points of the CAM build and run scripts here.
The header files, preproc.h and misc.h, as well as the directory search path file, Filepath, are needed for the CAM build procedure in an analogous manner to the CLM2.1 build procedure. The user should keep in mind that the CLM2.1 directory hierarchy MUST appear after the CAM directory hierarchy in Filepath. CLM2.1 contains several files that have the same name as the corresponding CAM files (e.g. time_manager.F90). When running in CAM mode, the corresponding CAM file must be used. The CAM build and run scripts ensure this.
The CLM2.1 namelist, clmexp, must also be specified. By default, RTM river routing is not enabled in cam mode (i.e. the cpp variable, RTM, is not defined). Furthermore, CLM2.1 does not permit the user to independently set several namelist variables (in particular, those dealing with history file logic and run control logic) when running in cam mode. CLM2.1 will override any user input for these variables with the corresponding values used by the CAM model. This is discussed in more detail in section 4.6.