Version 18 (modified by cbricaud, 8 years ago) (diff) |
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Trough grid refinement (AGRIF nesting & coarsening)
Last edition: Wikinfo(changed_ts)? by Wikinfo(changed_by)?
Work in progress
Coarsening of physics for biogeochemistery model
Presentation
A capacity of coarsening physics to force a BGC model coupled to NEMO has been developped in NEMO_3.6. This capacity allow to run 'online' a BGC model coupled to OPA-LIM with a lower resolution, to reduce the CPU coast of the BGC model, while preserving the effective resolution of the dynamics.
This capacity is not included in the NEMO_3.6 , but is available in a specific branch of the 3.6 stable. This branch is regularly phazed with the NEMO_3.6. An associated ticket to follow evolution is here.
A presentation is available here, where the methodology is presented.
How to ?
To activate the coarsening, key_crs should be added to list of cpp keys. This key will only activate the coarsening of dynamics.
Some parameters are available in the namelist_cfg:
! passive tracer coarsened online simulations !----------------------------------------------------------------------- nn_factx = 3 ! Reduction factor of x-direction nn_facty = 3 ! Reduction factor of y-direction nn_msh_crs = 0 ! create (=1) a mesh file or not (=0) nn_crs_kz = 3 ! 0, volume-weighted MEAN of KZ ! 1, MAX of KZ ! 2, MIN of KZ ! 3, 10^(MEAN(LOG(KZ)) ! 4, MEDIANE of KZ ln_crs_wn = .false. ! wn coarsened (T) or computed using horizontal divergence ( F ) ! ! ln_crs_top = .true. !coarsening online for the bio /
- Only nn_factx = nn_facty = 3 is available and the coarsening only works for grids with a T-pivot point for the north-fold lateral boundary condition( ORCA025, ORCA12,ORCA36,...).
- nn_msh_crs = 1 : will activate the generation of the coarsened grid meshmask.
- nn_crs_kz : is the operator to coarsene the vertical mixing coefficient.
- ln_crs_wn : when key_vvl is activated, this logical has no effect; the coarsened vertical velocities are computed using horizontal divergence.
when key_vvl is not activated, coarsened vertical velocities are computed using horizontal divergence ( ln_crs_wn = .false )
or coarsened vertical velocities are computed with an average operator ( ln_crs_wn = .true. )
- ln_crs_top = .true: should be activated to run BCG model in coarsened space; so only works when key_top is in the cpp list and eventually key_pisces or key_my_trc.
Choice of operator to coarsene KZ
A sensiblity test has been done with an Age tracer to compare the different operators. The 3 and 4 options seems to provide the best results.
Some results can be found [xxx here]
Example of xml files to output coarsened variables with XIOS
Attachments (4)
- crs_wiki_1.1.pdf (350.3 KB) - added by cbricaud 8 years ago.
- iodef.xml (8.0 KB) - added by cbricaud 8 years ago.
- file_def.xml (5.5 KB) - added by cbricaud 8 years ago.
- file_crs_def.xml (5.5 KB) - added by cbricaud 8 years ago.
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