Build-time variables

The env_build.xml file sets variables that control various aspects of building the model executable. Most of the variables should not be modified by users. The variables that you can modify are discussed in more detail below.


The CESM executable root directory. This is where the model builds its executable and by default runs the executable. Note that $EXEROOT needs to have enough disk space for the experimental configuration requirements. As an example, CESM can produce more than a terabyte of data during a 100-year run, so you should set $EXEROOT to scratch or tmp space and frequently back up the data to a mass storage device.


The directory where the executable will be run. By default this is set to $EXEROOT/run. RUNDIR allows you to keep the run directory separate from the build directory.


Valid values are TRUE and FALSE. The default is FALSE.

If FALSE, the component libraries are built with OpenMP capability only if the NTHREADS_ setting for that component is greater than 1 in env_mach_pes.xml.

If TRUE, the component libraries are always built with OpenMP capability.


Flag to turn on debugging for run time and compile time. Valid values are TRUE, FALSE. The default is FALSE.

If TRUE, compile-time debugging flags are activated that you can use to verify software robustness, such as bounds checking.

Important:: On IBM machines, floating point trapping is not activated for production runs (i.e., non-DEBUG), due to performance penalties associated with turning on these flags.


Number of processors for gmake (integer). 0 < GMAKE_J < [number of processors/node]. $GMAKE_J allows a faster build on multi-processor machines. If the build fails in different places without other changes, setting this to 1 may help.


A POP2-specific setting for turning on different ocean tracer modules. Valid values are any combination of: iage, cfc, ecosys.