Last edited Timestamp?

Author

Matthieu Leclair & Gurvan Madec

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Branch

DEV_r1837_MLF

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Description

Introduce the modified Leap-Frog Robert-Asselin filter to fit the one presented in Leclair and Madec Ocean Modelling (2009).

This update is part of the LOCEAN.8 task (Update of the ocean physics) due by June 25th

The main remaining modifications concern :

(1) forcing terms as a mean between time step n-1/2 and n+1/2 (sbcmod)

(2) Asselin filter: remove the forcing from the filter (dynnxt, tranxt, traqsr)

(3) tranxt.F90 : semi-implicit hydrostatic pressure gradient : change the coefficients to take into account the Asselin filter parameter

time mean T and S for the semi implicit hpg computation is now rbcp*ta+(2-rbcp)*tn+rbcp*tb with rbcp=(1+atfp)*(1+atfp*atfp) / 4, and atfp is the Asselin filter parameter. It used to be (ta+2*tn + tb) / 4.

The effect of the change is to further extend the stability limit of the time stepping scheme when ln_dynhpg_imp = T

Current missing points

(1) and (2)

(3) open question in vvl case : thickness weighted tracer in the time mean, do we need to compute and use a time mean thickness in the hpg computation?

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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........

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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.......

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Resources

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

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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..........