# From v3.6 to v4.2.x on mixing coefficients (missing \`key\_dynspg\_ts\`) **URL:** \ **Category:** Versions\ **Tags:** DYN\ **Created:** [30 March 2022 21:02 UTC](https://nemo-ocean.discourse.group/t/from-v3-6-to-v4-2-x-on-mixing-coefficients-missing-key-dynspg-ts/255 "2022-03-30T21:02:39Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![qtqw](https://avatars.discourse-cdn.com/v4/letter/q/77aa72/32.png) [@qtqw](https://nemo-ocean.discourse.group/u/qtqw)\ **Post date:** [30 March 2022 21:02 UTC](https://nemo-ocean.discourse.group/t/from-v3-6-to-v4-2-x-on-mixing-coefficients-missing-key-dynspg-ts/255/1 "2022-03-30T21:02:39Z")
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 ```fortran 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? ---
**Author:** ![ntmlod](https://yyz2.discourse-cdn.com/free1/user_avatar/nemo-ocean.discourse.group/ntmlod/32/6_2.png) [@ntmlod](https://nemo-ocean.discourse.group/u/ntmlod)\ **Post date:** [31 March 2022 10:59 UTC](https://nemo-ocean.discourse.group/t/from-v3-6-to-v4-2-x-on-mixing-coefficients-missing-key-dynspg-ts/255/2 "2022-03-31T10:59:38Z")
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://forge.ipsl.jussieu.fr/nemo/wiki/Changelog) [https://sites.nemo-ocean.io/user-guide/changes.html](https://sites.nemo-ocean.io/user-guide/changes.html) [https://sites.nemo-ocean.io/user-guide/migration.html](https://sites.nemo-ocean.io/user-guide/migration.html) ---
**Author:** ![jchanut](https://yyz2.discourse-cdn.com/free1/user_avatar/nemo-ocean.discourse.group/jchanut/32/9_2.png) [@jchanut](https://nemo-ocean.discourse.group/u/jchanut)\ **Post date:** [31 March 2022 12:11 UTC](https://nemo-ocean.discourse.group/t/from-v3-6-to-v4-2-x-on-mixing-coefficients-missing-key-dynspg-ts/255/3 "2022-03-31T12:11:17Z")
The way diffusion/viscosity coefficients are set has indeed changed. This is fully detailed in the documentation you can find here (page 124): > **[NEMO ocean engine](https://zenodo.org/record/6334656)** > > The ocean engine of NEMO is a primitive equation model adapted to regional and global ocean circulation problems. It is intended to be a flexible tool for studying the ocean and its interactions with the others components of the earth climate system... ---
**Author:** ![qtqw](https://avatars.discourse-cdn.com/v4/letter/q/77aa72/32.png) [@qtqw](https://nemo-ocean.discourse.group/u/qtqw)\ **Post date:** [1 April 2022 13:20 UTC](https://nemo-ocean.discourse.group/t/from-v3-6-to-v4-2-x-on-mixing-coefficients-missing-key-dynspg-ts/255/4 "2022-04-01T13:20:52Z")
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 ```nohighlight 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? ---
**Author:** ![jchanut](https://yyz2.discourse-cdn.com/free1/user_avatar/nemo-ocean.discourse.group/jchanut/32/9_2.png) [@jchanut](https://nemo-ocean.discourse.group/u/jchanut)\ **Post date:** [1 April 2022 13:54 UTC](https://nemo-ocean.discourse.group/t/from-v3-6-to-v4-2-x-on-mixing-coefficients-missing-key-dynspg-ts/255/5 "2022-04-01T13:54:40Z")
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](https://sites.nemo-ocean.io/user-guide/install.html#create-and-compile-a-new-configuration)