Changes between Version 7 and Version 8 of Users/Model Interfacing/Biogeochemistry Coarsening


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Timestamp:
2017-05-30T15:48:11+02:00 (3 years ago)
Author:
cbricaud
Comment:

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  • Users/Model Interfacing/Biogeochemistry Coarsening

    v7 v8  
    44 
    55 
     6= Coarsening of physics for biogeochemistery model = 
    67 
    7  
    8 = Coarsening of physics for biogeochemistery model = 
     8== Presentation == 
    99 
    1010A 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. 
     
    1212 
    1313This capacity is not included in the [https://forge.ipsl.jussieu.fr/nemo/browser/branches/2015/nemo_v3_6_STABLE/NEMOGCM NEMO_3.6] , but is available in a specific [https://forge.ipsl.jussieu.fr/nemo/browser/branches/2015/dev_r5003_MERCATOR6_CRS branch] of the 3.6 stable. This branch is regularly phazed with the NEMO_3.6. 
     14An associated ticket to follow evolution is  [https://forge.ipsl.jussieu.fr/nemo/ticket/1426 here]. 
     15 
     16A presentation is available [xxx here], where the methodology is presented. 
     17 
     18 
     19== How to ? == 
     20 
     21To activate the coarsening, key_crs should be added to list of cpp keys. This key will only activate the coarsening of dynamics. 
     22 
     23Some parameters are available in the namelist_cfg: 
     24 
     25 
     26{{{ 
     27               !   passive tracer coarsened online simulations 
     28!----------------------------------------------------------------------- 
     29   nn_factx    = 3         !  Reduction factor of x-direction 
     30   nn_facty    = 3         !  Reduction factor of y-direction 
     31   nn_msh_crs  = 0         !  create (=1) a mesh file or not (=0) 
     32   nn_crs_kz   = 3         ! 0, volume-weighted MEAN of KZ 
     33                           ! 1, MAX of KZ 
     34                           ! 2, MIN of KZ 
     35                           ! 3, 10^(MEAN(LOG(KZ))  
     36                           ! 4, MEDIANE of KZ  
     37   ln_crs_wn   = .false.   ! wn coarsened (T) or computed using horizontal divergence ( F ) 
     38                           !                           ! 
     39   ln_crs_top = .true.     !coarsening online for the bio 
     40/ 
     41}}} 
     42 
     43- '''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,...). 
     44 
     45- '''nn_msh_crs  = 1''' : will activate the generation of the coarsened grid meshmask. 
     46 
     47- '''nn_crs_kz''' : is the operator to coarsene the vertical mixing coefficient.  
     48 
     49- '''ln_crs_wn''' : when key_vvl is activated, this logical has no effect;  the coarsened vertical velocities are computed using horizontal divergence. 
     50              when key_vvl is not activated, coarsened vertical velocities are computed using horizontal divergence ( ln_crs_wn   = .false )  
     51                                             or coarsened vertical velocities are computed with an average operator ( ln_crs_wn   = .true. ) 
     52- '''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. 
     53 
     54 
     55== Choice of operator to coarsene KZ ==  
     56 
     57A sensiblity test has been done with an Age tracer to compare the differents operagtor. 10^(MEAN(LOG(KZ)) or MEDIANE of KZ seems to provide the best resultats. 
     58 
     59Some results can be found [xxx here] 
     60