Tidy neutral physics in input.nml

[aekiss]

Following https://arccss.slack.com/archives/C9Q7Y1400/p1588727336089300

MOM's neutral physics settings in &ocean_nphysics_util_nml in input.nml are confusing because many ignored parameters are specified.

The ACCESS-OM2 configurations are explained in section 3.2.5 of the technical report, and the relevant code is ocean_nphysics_util.F90.

Here are the changes I think should be made to clarify &ocean_nphysics_util_nml in input.nml:

for the 0.1 deg configurations:

• remove everything in ocean_nphysics_util_nml - ignored because use_this_module = .false. in &ocean_nphysics_nml

for the 1 deg and 0.25 deg configurations:

• remove agm - ignored because agm_closure = .true.
• remove rossby_radius_min and rossby_radius_max - ignored because agm_closure_length_rossby = .false.
• remove agm_closure_eden_gamma - ignored because agm_closure_eden_greatbatch = .false.
• remove vel_micom - ignored because tracer_mix_micom = .false.
• remove agm_damping_time - ignored because agm_smooth_time = .false.
• remove these because they take the default value .false.
  • agm_closure_length_rossby
  • agm_closure_eden_greatbatch
  • tracer_mix_micom
  • agm_closure_length_fixed
  • drhodz_smooth_horz
  • drhodz_smooth_vert
  • agm_closure_length_bczone
  • agm_smooth_space
  • agm_smooth_time

Does this look OK @russfiedler, @rmholmes, @AndyHoggANU ?

[AndyHoggANU]

Looks OK to me. Thanks.

[StephenGriffies]

@aekiss I agree with removing those nml options that are not used in the configuration. neutral physics has heaps of options and best to focus just on those that are used by the configuration.

[rmholmes]

Good idea, thanks Andrew.

I imagine there is many similar non-neccessary default options in lots of the other namelists where a similar thing could be done.

[aekiss]

Agreed, there is plenty more redundancy in the namelists. Checking them is a bit of a tedious slog though (e.g. some defaults are true rather than false, etc)...

[aekiss]

Closed - I've made these changes in the ak-dev branches in all JRA configs