Links to downloadable versions of the configuration and input files for active versions of ORCA1 are provided at the bottom of this page but please browse the following paragraphs to ensure that you collect the correct configuration files to match your needs.
The source files files are independent of the vertical grid. The ORCA1 configuration can be enabled using the new key: key_orca_r1. Prior to v3.3, a 42 level grid, with depths closely matching those used in the Hadley Centre's HadGOM1 model, was the default choice and this was configured by adding the following preprocessor key to the P_P setting in the Makefile prior to compilation:
However, other vertical grids were defined and these could be accommodated within the ORCA1 configuration by assigning a particular integer value to the key.
For example, following discussions with Anne-Marie Treguier in August 2006, we agreed a 64 level vertical grid which matched requirements for projects at IFREMER and is very similar to the OCCAM vertical resolution. This configuration was supported without the introduction of new keys or modules with some preprocessing directives in par_ORCA_R1.h90. The relevant code snippets can be viewed here. This alternative vertical grid was enabled by setting the preprocessor key to 64 with the following setting in the Makefile.:
A 46 level configuration was also introduced which is compatible
with the DRAKKAR projects ORCA025 and ORCA05 configurations. This was enabled by:
Any other value would default to the 42-level grid but more alternatives could
be supported by using the
#elif preprocessor construct.
The following graph compares the level thicknesses for the 42 and other configurations. The standard ORCA2 vertical grid (31 levels) is also shown for comparison. Click on the image to obtain a larger version.
To avoid confusion the ftp links for files particular to any one vertical grid are listed on separate pages. The following links list the files which are independent of the vertical grid:
From v3.3 onwards, basic support for the ORCA1 configuration is included in the tagged release. Please note however, the ORCA1 is not a reference configuration which means that newly introduced features and parameterisations will not necessarily have been tested with the ORCA1 configuration. Any problems should be reported to the NEMO system team but a rapid response can not be guaranteed. For simplicity, from v3.3 onwards only two vertical grids are supported in the tagged release. These are the 46-level Drakkar configuration (default) and the new 75-level configuration which uses a double-tanh function to obtain a 1m vertical resolution at the surface (key_orca_r1=75). See the code snippets page for the parameter settings required if you wish to reintroduce either the 64-level or 42-level cases. Both these grids used the single tanh function so changes should be made by copying and altering the default (46-level) case.
The following are the modified source code modules required to configure and run the ORCA1 configuration with earlier versions of NEMO. The versions provided are compatible with the v3.2 release of NEMO (Paris revision 1780 to be precise). The modules are available in complete form in a tar file or as a UNIX patch file:
NEMO/NST_SRC/agrif_user.F90 NEMO/OFF_SRC/par_oce.F90 NEMO/OPA_SRC/DOM/domzgr.F90 NEMO/OPA_SRC/DOM/dommsk.F90 NEMO/OPA_SRC/DOM/domhgr.F90 NEMO/OPA_SRC/LDF/ldfdyn_c2d.h90 NEMO/OPA_SRC/SBC/sbcrnf.F90 NEMO/OPA_SRC/par_ORCA_R1.h90 NEMO/OPA_SRC/DIA/diaptr.F90 NEMO/OPA_SRC/DIA/diafwb.F90 NEMO/OPA_SRC/par_oce.F90
sbcfwb.F90 - Reported bug fix to emp correction (not currently used) sbcssr.F90 - Fixed support for nn_ssr=2 option and added enhanced relaxation under ice trazdf.F90 - Added check to prevent negative salinities that can occur (rarely) near Arctic river mouths.
Finally, to obtain a complete configuration, please select files from one of the following sets:
Note only the first two configurations are supported "out of the box" with the tagged releases from v3.3 onwards. The 64 and 42 level versions are provided as legacy versions but their use will require code additions to par_ORCA_R1.h90 in order to obtain the correct vertical grid.