Changes between Initial Version and Version 1 of 2014WP/2014_System Simplification_v2


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Timestamp:
2013-11-20T12:18:51+01:00 (7 years ago)
Author:
gm
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  • 2014WP/2014_System Simplification_v2

    v1 v1  
     1'''Note on possible system simplification''' 
     2 
     3'''Motivation''': 
     4 
     5We need to simplify the code for maintenance, robustness and future evolution (change in time stepping, …etc). This means fewer options, and a consensus on the default (and thus well validated) set of numerics. 
     6 
     7The idea is to change the current most used choices from :  
     8 
     9linear filtered free surface zps ocean with TVD, "Madec" isoneutral diffusion, and standard equation of state ;  levitating sea-ice with virtual salt fluxes 
     10 
     11possibly to : 
     12 
     13Non linear (vvl), split-explicit (ts) free surface, mixte zps/s-coordinate ocean with 3rd order advection (UBS),  "Griffies" isoneutral diffusion ; embedded multi-category sea-ice (exact fluxes). 
     14 
     15And this with a removing of obsolescent features and a cleaning of the code. 
     16 
     17Timing: ideally, no more than 2 years from now (to be ready for CMIP6, and on time for the foreseen evolution of the time stepping) 
     18 
     19'''* core action (supported by all system team)''' 
     20 
     21'''- desired, but subject to discussion ''' 
     22 
     23'''? feasible but all conditions required are not yet met  ''' 
     24 
     25'''CHANGE in paradigm''' 
     26 
     27'''*''' • default : non-linear free surface ('''planned''' '''in 2014''') 
     28 
     29'''*''' • remove filtered free surface and all associated solvers (if yes when? 2014?) 
     30 
     31                (required AGRIF with time-splitting, '''done''' in 2013) and deeply tested ('''planned''' 2014) 
     32 
     33'''*''' • vertical coordinate : default option mixte zps/s-tilde coordinate (thus with variable volume level), with mixte zps*/s*, mixte z/s, zps, z and s coordinate system as sub-option (same code used) (2014-2015 ?) 
     34 
     35                - tracer solved as thickness weighted tracer: D,,t,,(e,,3t,, T) ('''planned''' '''2014''') 
     36 
     37                - thickness weighted quantities in the outputs ('''planned''' '''2014''') 
     38 
     39                - no more substitute (domzgr_substitute.h90): all e3 always defined at before, now and after time steps ('''partly done''' in 2013, '''achieved''' in 2014).   
     40 
     41                - adapte OFF line for tracer to variable volume (2015?)  
     42 
     43'''*''' • linear ssh option set without optimization (i.e. starting from the non-linear case with minimal changes, not optimal changes), or linear case suppressed ?? We should probably keep a linear case for test cases. (2014-2015 ?) 
     44 
     45'''*''' • sea-ice : embedded sea-ice as default 
     46 
     47                - suppress levitating sea ice with virtual salt fluxes. (2014 ?) 
     48 
     49                - Suppress levitating sea ice with mass exchange (?)  CICE issue… 
     50 
     51                - need land-fast ice ('''planned''' '''2014''') 
     52 
     53                - need BDY compatibility with embedded sea-ice …. (who when?) 
     54 
     55'''-''' • tracer advection scheme: diminish their number (?). Typically one module for 2^nd^/4^th^ order and one for a 3^rd^ order scheme, both associated with an optional flux limiter to ensure positivity. 
     56 
     57'''-''' • vertical physics:  simplification versus diversity 
     58 
     59                - keep only one (GLS) ? or maintain some diversity?  
     60 
     61                - KPP remove unless if-less KPP is implemented (Lemarié et al 2012). Keeping a validated KPP scheme in the system make sense for comparison purposes.  
     62 
     63                - suppress or keep the explicit vertical diffusion 
     64 
     65'''OBSOLESCENT features''' 
     66 
     67mains: 
     68 
     69'''*''' • remove LIM2 : only LIM3 remains in the system (planed 2014) 
     70 
     71'''*''' • remove OBC : only BDY remains in the system (planed 2013, early 2014) 
     72 
     73'''*''' • remove OASIS 3 and 4 :  OASIS-MCT (planed 2014) 
     74 
     75'''-''' • duplicate isoneutral operator: keep only the Griffies' one (tests needed before decision, tests planed in 2014 NOCS+LOCEAN)  
     76 
     77smaller one 
     78 
     79'''-''' • Non-penetrative convection : either correct it (using alpha & beta) or remove it (who?) 
     80 
     81'''*''' • remove acceleration of convergence (notably rdttra=F(k) ==> unique rdt) 
     82 
     83'''*''' • remove Neptune effect : ORCA1 runs shows its inefficiency. 
     84 
     85'''-''' • Smagorinsky (?) : use 3rd order operator (UBS) instead and remove it ? 
     86 
     87I/O  
     88 
     89'''-''' • remove Dimg format (?) (agreement needed from DRAKKAR group)  
     90 
     91'''?''' • remove IOIPSL : 2 issues, still use in some places, and XIOs portability… (''probably much too early to decide that'') 
     92 
     93'''*''' • use of XIOS logical to control the computation of diagnostics (2014-2015, '''who?''') 
     94 
     95'''CODE cleaning''' 
     96 
     97'''*''' • OBS operator : clean the stand-alone implementation ('''planned 2014''') 
     98 
     99'''*''' • suppress most of the CPP keys, if not all of them (2015 ?) 
     100 
     101'''*''' • dynamical allocation: return back to standard allocation (?) (no more '''CALL '''wrk_alloc and '''CALL '''wrk_dealloc)  Evaluation to decided what to do ('''planned 2014''') 
     102 
     103'''*''' • no more potential density (zdfnpc and MLD computed from alpha & beta) ('''planned''' '''2014''') 
     104 
     105'''*''' • remove all hard coded specific alterations associated with configurations (ORCA,…) while introducing associated input files (2015 ?) 
     106 
     107'''*'''         • same for the definition of coordinate system (s, mixed z-s): only a simple case hard coded. For more sophisticated cases, the required information should be  read in an input file. (2015 ?) 
     108 
     109'''*''' • avm defined at t-point ==> suppress avmu, avmv and ~10 lbc_lnk calls (2015 ?) 
     110 
     111'''-''' • LDF: remove 1D and 2D cases, keep only 3D ; laplacian and bilaplacian coefficients defined at the same points (T and F) ;  time varying coefficients (Smagorinsky, function of growth rate of baroclinic instabilities): better integration rather than configuration dependent cases (2015 ?)