GLOBPEA – Atmospheric model

GLOBPEA is the main component of the CCAM system and simulates the atmosphere, land-surface, (optionally) ocean and (optionally) sea-ice.  The CCAM namelist is separated into the following sections, where the link to each page explains the functions of those options 

CCAM is usually called with MPI according to

mpirun -np $nproc globpea

where $nproc is the number of processes.  It is possible to specify the namelist read by CCAM using the -c switch.  Otherwise the namelist is assumed to be called ‘input’.

CCAM also supports OpenMP and OpenACC for accessing additional threads and GPUs, if specified when the model is compiled. GPUs are detected automatically and are divided between the available CPUs on a node. Additional threads can be specified in the usual way.

mpirun -np $nproc -x OMP_NUM_THREADS=$nthreads -x OMP_STACKSIZE=512m -x OMP_ globpea

CCAM will decrease the number of CPUs in use to satisfy its requirements for grid decomposition. In this way, $nproc is simply a recommendation as an upper limit on the number of CPUs that can be used for the simulation.

The following links describe the CCAM namelist options