Changes between Version 15 and Version 16 of 2020WP/KERNEL-06_techene_better_e3_management


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Timestamp:
2020-08-21T12:59:41+02:00 (5 months ago)
Author:
techene
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  • 2020WP/KERNEL-06_techene_better_e3_management

    v15 v16  
    2525=== Description 
    2626 
    27 NEMO current version requires memory for scale factor storage e3[P] at P-point computation uses interpolation of the e3t 4D table at P = {u-, v-, w-, f-, uw-, vw-} points. This means 7 4D tables stored in memory. The idea consists in computing scale factors e3[P](ji,jj,jk,Ktl)on the fly with r3[P] = ssh[P] / h_0 and e3[P]_0 instead of using memory. This should help to improve run time when running parrallel. Indeed, processors have as least two memory level : fast memory and slow RAM memory. In parrallel runs the processing time is no longer limited by computation time but by memory access time. That is the reason why trying to minimise memory buffering.  
     27NEMO current version requires memory for scale factor storage e3[P] at P-point computation uses interpolation of the e3t 4D table at P = {u-, v-, w-, f-, uw-, vw-} points. This means 7 4D tables stored in memory. The idea consists in computing scale factors e3[P](ji,jj,jk,Ktl)on the fly with r3P = ssh[P] / h_0 and e3[P]_0 instead of using memory. This should help to improve run time when running parrallel. Indeed, processors have as least two memory level : fast memory and slow RAM memory. In parrallel runs the processing time is no longer limited by computation time but by memory access time. That is the reason why trying to minimise memory buffering.  
    2828Asselin filter management is done recomputing r3[P] directly with the filtered ssh. 
    2929z-tilde management is done through e3[P]_0 that may varies with time in the z-tilde case. 
     
    8484}}} 
    8585 
    86 ==== developpments  
    87  
    88 In version 1 of source://dev_r12377_KERNEL-06_techene_e3 we implement changes progressively and validate step by step regarding GYRE_PISCES test case. We remove all the vvl routines usage thus we replace e3t/u/v/w/uw/vw at 3 time step + e3f (19) 3d tables storage and twice e3u/v "after" + e3u/v "now" + e3f/w/uw/vw "now" + e3w/uw/vw "before" (13) 3d tables interpolation at each step and e3u/v/f/w/uw/vw "now" + e3u/v/w/uw/vw "before" (11) 3d tables interpolation at initialisation or restart by r3t/u/v at 3 time steps and r3f i.e. (10) 2d table storage and on the fly light computation. For backward compatibility we introduce a cpp key key_qco in order to isolate new scale factor implementation from former vvl version. qco stand for for "quasi eulerian coordinate".  
     86==== developments  
     87 
     88In version 1 of source:/NEMO/branches/2020/dev_r12377_KERNEL-06_techene_e3 we implement changes progressively and validate step by step regarding GYRE_PISCES test case. We remove all the vvl routines usage thus we replace e3t/u/v/w/uw/vw at 3 time step + e3f (19) 3d tables storage and twice e3u/v "after" + e3u/v "now" + e3f/w/uw/vw "now" + e3w/uw/vw "before" (13) 3d tables interpolation at each step and e3u/v/f/w/uw/vw "now" + e3u/v/w/uw/vw "before" (11) 3d tables interpolation at initialisation or restart by r3t/u/v at 3 time steps and r3f i.e. (10) 2d table storage and on the fly light computation. For backward compatibility we introduce a cpp key key_qco in order to isolate new scale factor implementation from former vvl version. qco stand for for "quasi eulerian coordinate".  
    8989- new variables added in dom_oce and domain  
    9090{{{ 
     
    146146NEMO intermediate version 1 implements scales factors computed from sea surface interpolation (2d field) instead but the whole structure of the code remains. Note that to validate "NEMO intermediate version 1" we change the code line by line and compare results of GYRE configuration with TOP de-activated. Differences in the results appear when changing the W-point scale factor interpolation from T-point scale factor into the sea surface scaling since the bottom level is not considered in the same way. Indeed for GYRE configuration e3w_0 are not the half sum of e3u_0, so the way it is implemented in the reference version is not convinient...  
    147147[Etape 1] 
    148  
    149148NEMO intermediate version 2 implements scales factors computed from sea surface interpolation (2d field) instead. The initialisation compute sea surface to h_0 called r3 coefficients (which are 2d). These r3 coefficients are updated after each sea surface modification (after time splitting and asselin filtering) and interpolated at U-V-F-points using new but similar routines as  domvvl routines. An extra substitute routine helps to substitute each e3 to its expression (e3P_0 ( 1 + r3P ) * maskP). Sea surface filtering is displaced before Asselin filtering of speed (u,v) and tracer. This version 2 should give exactly the same results as version 1 and it does ! 
    150149[Etapes 2 & 3] 
    151  
    152150NEMO intermediate version 3 deals with cleanning the code by adding the substitution and removing e3 computation along the code of OCE. It also takes care of the lines lenghts that should be shorter than 136 caracters, some are missing...  
    153151[Etapes 4 & 5] 
    154  
    155152In order to take into account the new index/loop management, NEMO intermediate version 4 consists in merging the results with trunk 12698 the resulting revision is 12724. Note that in this new trunk revision Jerome changed the way to deal with Asselin filter (traatf and dynatf), intermediate version 4 needs to adapt accordingly. 
    156153[Etape 6] 
    157  
    158154NEMO intermediate version 5 implements a clean way to deal with the key_qco and also deals with the removal of gde* and h* of memory. It removes e3 from the whole code, to deal with TOP there is to play with pointer of the sea surface height and change where it is computed in step.  
    159155[Etape 7] 
    160  
    161156RUN SETTE and deliver version for mid-merge party ! Some silly allocating memory bugs found and a not that silly bug in the implicit mode for SPITZ12 configuration.  
    162157[Etape 8, 9 & 11]