From v3.6 to v4.2.x on mixing coefficients (missing `key_dynspg_ts`)

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1

I am transitioning from old NEMO 3.6 to new 4.2.
I found that there are minor modifications in namelist_ref and namelist_cfg files.
For example, in NEMO 3.6 were coefficients

   rn_aht_0         =  -5.e+8    !  horizontal eddy diffusivity for tracers [m2/s]
   rn_ahm_0_blp     =  -5.e+9    !  horizontal bilaplacian eddy viscosity [m4/s]

that seem to be absent in NEMO 4.2.
Is there any way to set these coefficients in new NEMO?

2

I’m not able to answer your point precisely however you can find useful informations from the following pages:
https://forge.ipsl.jussieu.fr/nemo/wiki/Changelog
https://sites.nemo-ocean.io/user-guide/changes.html
https://sites.nemo-ocean.io/user-guide/migration.html

3

The way diffusion/viscosity coefficients are set has indeed changed. This is fully detailed in the documentation you can find here (page 124):

4

Thank you for the replay.
I have one more question about compiling the new NEMO.
I have difficulty creating new configuration.
With NEMO 3.6 I used the command
./makenemo -m ifort_linux -r OPA_SRC -n MY_CONFIG -j 8

However with NEMO 4.2 it doesn’t work.
I create NEMOGCM/cfgs/MY_CONFIG/cpp_MY_CONFIG.fcm with fppkeys. Then I try
./makenemo -m ifort_linux -r OCE -n MY_CONFIG -j 8
but it fails with the message

E R R O R : key key_dynspg_ts is not found in MY_CONFIG/WORK routines...
we stop...

How can I create new configuration based on OCE subcomponent?

5

As your error message says, the cpp key key_dynspg_ts does not exist anymore. It is replaced by a logical flag in your namelist ln_dynspg_ts=.true.
You may have a look at other reference configurations shipped with NEMO and find useful tips in the user guide here:

https://sites.nemo-ocean.io/user-guide/install.html#create-and-compile-a-new-configuration