Skilled (#3) - [FAQ] Choosing options (natural and computer science), please read this before creating a new topic (#9) - Message List

[FAQ] Choosing options (natural and computer science), please read this before creating a new topic
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FAQ : Choosing options (natural and computer science)

Last edition: 08/10/20 08:29:15 by

Please check the information in this page before creating a new item in this forum. The list of questions and answer is available in the page outline on the right side of this page

Selecting NEMO options

How to select NEMO options?

NEMO options are set using a combination of cpp keys (e.g. key_top, key_lim etc) and namelist settings. If you change a cpp key then you will need to recompile the code for the change to take effect. Namelist changes are applied when the model is run and the model does not need to be recompiled. Further information on cpp keys and namelists can be found in the reference manual

Which namelist should I edit?

For each component of nemo there are two namelists: namelist_ref and namelist_cfg. Users should only modify namelist_cfg and should leave namelist_cfg unset. Only values that are different between namelist_ref and your configuration need to appear in namelist_cfg. This setup has the advantage that namelist_cfg is much more concise and readable.


Natural science options

Ocean dynamics NEMO-OPA

New FAQs will be added here

Ocean tracers and biogeochemistry NEMO-TOP

New FAQs will be added here

Ocean sea-ice NEMO-LIM

New FAQs will be added here

Others

New FAQs will be added here


Computer and HPC science options

Do I need to use cpp key key_nosignedzero?

If your compiler is fully F95 compliant (gfortran or crayftn for example), you need to overwrite the intrinsic SIGN function by activating the cpp key key_nosignedzero (see list of active cpp keys in Model install. If you are not sure then you can compile NEMO without key_nosignedzero and try to run the model. If you see the following error message:

nemo_ctl: The intrinsec SIGN function follows 
          f2003 standard.
          Compile with key_nosignedzero enabled

then you will need to recompile with key_nosignedzero.

The SIGN function is re coded in lib_fortran and activated when the key is active, meaning that

USE lib_fortran

should appear in each module where the SIGN function is used.

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