1.3 External Software and Libraries

The CSIM code includes references to subroutines and libraries not contained in models/ice/csim4. This code is described in the following sections.

1.3.1 CCSM Share Code

CSIM uses some of the CCSM shared-code modules that are included in the models/csm_share directory. The share-code modules presently used in CSIM are:

• shr_const_mod.F90 - This module contains the "shared constants" that are used by all components for CCSM. Note that these constants are not used for the uncoupled ice model, which uses those set in ice_constants.F.

• shr_kind_mod.F90 - This module defines variable precision used by other shared-code modules.

• shr_msg_mod.F90 - This contains subroutines that provide an architecture-independent means of interacting with the operating system. CSIM uses the following subroutines from this module:
  • shr_msg_chdir - changes current working directory
  • shr_msg_dirio - redirects standard input and output to named files

• shr_mpi_mod.F90 - used by shr_sys_mod.F90

• shr_sys_mod.F90 - This contains subroutines that provide an architecture-independent means of interacting with the operating system. CSIM uses the following routines from this module:
  • shr_sys_flush - clears the print buffer
  • shr_sys_abort - provides a consistent stopping mechanism for multiple processors

1.3.2 netCDF Library

The netCDF library is necessary to run CSIM. The slab ocean mixed layer model and the prescribed ice model (not supported in this release) read in forcing data from netCDF files. The output history files are also written in this format. The history files conform to the NetCDF Climate and Forecast (CF) Metadata Conventions (http://www.cgd.ucar.edu/cms/eaton/cf-metadata/index.html). All of the netCDF-specific code used to write the history files is in subroutine icecdf in module ice_history.F. Machine dependent information that sets the location of the netCDF library is set in the models/bld/Macros.* for the coupled model, and in models/ice/csim4/src/bld/Macros.* for the uncoupled ice model.

1.3.3 Message Passing Interface (MPI)

CSIM intra- and inter-model communications are conducted via MPI. The MPI library is automatically loaded during the CCSM build procedures.