Last edited Timestamp?

Author : Tim Graham

ticket : #1296

Branch : BRANCH_NAME

---

Description

Development of a new module to carry out masked damping tracer fields. The mask will be read in from an external netCDF file.

The module will eventually replace the tradmp module in which there are several hard coded options for different grids.

Plan

Requirements:

1) Damping climatologies can be different to climatological start files - use separate version of dia_tsd_read or implement new version?
2) No grid dependence - controlled by mask file only
3) Region entirely specified by mask file (both horizontal and vertical)
4) Mask file can be used for varying coefficient (use values between 0 and 1) - i.e. 0 for no relxation or 1 for relaxation at the time scale specified in namelist
5) Should work with VVL
6) Make sure only one of tra_dmp or tra_rlx is used at one time.

Namelist requirements:

'Namelist requirements:
Although a new namelist section is needed this will eventually be a replacement for tra_dmp so still a simplification
Needs:
1) Mask file name
2) Relaxation time scale (in seconds or timesteps?)
3) Switch to damp in full column/only in mixed layer/only below mixed layer - this is current functionality that can't be reproduced using a maskfile.
4) Mask variable name?

Subroutines:

• Copy of dia_tsd_read or modify dia_tsd_read to allow it to be used with different files (after initial conditions have been read)
  - tra_rlx_init:
      read the namelist, read the mask file, calculate restoration coefficient
  - tra_rlx:
      Calculate the trend at each point = rlx_mask * resto * (zts_dta - tsb)  (where zts_dta is the climatological value, resto is the restoration coefficient) and add to total trend
      The climatology that we are relaxing to should be on the original model grid. Given the long time scales of the climatology compared to variations in SSH it seems reasonable not worry about the slight changes in vertical grid spacing.
  - Link to trends diagnostics to output the trends?

---

Testing

Testing could consider (where appropriate) other configurations in addition to NVTK].

NVTK Tested	'''YES/NO'''
Other model configurations	'''YES/NO'''
Processor configurations tested	[ Enter processor configs tested here ]
If adding new functionality please confirm that the New code doesn't change results when it is switched off and ''works'' when switched on	'''YES/NO/NA'''

(Answering UNSURE is likely to generate further questions from reviewers.)

'Please add further summary details here'

• Processor configurations tested
• etc----

Bit Comparability

Does this change preserve answers in your tested standard configurations (to the last bit) ?	'''YES/NO '''
Does this change bit compare across various processor configurations. (1xM, Nx1 and MxN are recommended)	'''YES/NO'''
Is this change expected to preserve answers in all possible model configurations?	'''YES/NO'''
Is this change expected to preserve all diagnostics? ,,''Preserving answers in model runs does not necessarily imply preserved diagnostics. ''	'''YES/NO'''

If you answered '''NO''' to any of the above, please provide further details:

• Which routine(s) are causing the difference?
• Why the changes are not protected by a logical switch or new section-version
• What is needed to achieve regression with the previous model release (e.g. a regression branch, hand-edits etc). If this is not possible, explain why not.
• What do you expect to see occur in the test harness jobs?
• Which diagnostics have you altered and why have they changed?Please add details here........

---

System Changes

Does your change alter namelists?	'''YES/NO '''
Does your change require a change in compiler options?	'''YES/NO '''

If any of these apply, please document the changes required here.......

---

Resources

''Please ''summarize'' any changes in runtime or memory use caused by this change......''

---

IPR issues

Has the code been wholly (100%) produced by NEMO developers staff working exclusively on NEMO?

'''YES/ NO '''

If No:

• Identify the collaboration agreement details
• Ensure the code routine header is in accordance with the agreement, (Copyright/Redistribution? etc).Add further details here if required..........