Author: '''Jérôme Chanut, Mercator Océan''' Page related to ticket: #1620 and associated to the following development branch: [​https://forge.ipsl.jussieu.fr/nemo/browser/branches/2015/dev_r5847_MERCATOR9_solveur_simplification] This development is part of the shared simplication process, task: SIMPLIF-2: Removal of filtered free surface. Split explicit and explicit free surface only. '''Step 1: Remove filtered free surface option and associated key_dynspg_flt key''' 1) Remove parts of the code specific to "key_dynspg_flt" or lk_dynspg_flt=T and the need for solver modules in the code.[[BR]] 2) Suppress SOL directory and dynspg_flt module[[BR]] 3) Clean momentum trend routines related to filtered free surface (trddyn, trdken, trd_oce).[[BR]] 4) Update reference configurations: [[BR]] * Replace key_dynspg_flt by key_dynspg_ts if needed in CONFIG/* directories. [[BR]] * Remove namsol block in namelist_* and references to flt variables (trends) in field_def.xml[[BR]] * SETTE: update sette.sh, to remove modifications of namelist variables related to solver. [[BR]] NB: one should change "solver.stat" file and numsol names in stp_ctl and in_out_manager... keep it as is for the time being[[BR]] ==> '''Commit changes to revision 5868''' [https://forge.ipsl.jussieu.fr/nemo/changeset?old_path=%2Fbranches%2F2015%2Fdev_r5847_MERCATOR9_solveur_simplification&old=5867&new_path=%2Fbranches%2F2015%2Fdev_r5847_MERCATOR9_solveur_simplification&new=5868] '''Step 2: Suppress implicit pressure gradient option, ln_hpg_imp=T ''' Since this option is not supported with the now default split explicit free surface: remove it ( => simpler step routine). ln_hpg_imp namelist variable suppressed in reference namelist.[[BR]] ==> '''Commit changes to revision 5869'''[ https://forge.ipsl.jussieu.fr/nemo/changeset?old_path=%2Fbranches%2F2015%2Fdev_r5847_MERCATOR9_solveur_simplification&old=5868&new_path=%2Fbranches%2F2015%2Fdev_r5847_MERCATOR9_solveur_simplification&new=5869] '''Step 3: Time Stepping readibility / cleaning '''[[BR]] 1)''' dynzdf'''[[BR]] Make time stepping identical in explicit or split-explicit cases => assume that "after" velocities not tendencies are available after vertical diffusion of momentum (as for tracers) => modify dynzdf/dynnxt routines 2) '''step'''[[BR]] * Group all dynamical trends at the same place (at the beginning of the time stepping). Still keep dynnxt after tracer time stepping at the end.[[BR]] * Assuming ua/va are not used anymore during tracer computation as working arrays, remove temporary 3d arrays ua_sv, va_sv 3) '''Suppress obsolete''' dynspg_oce module, '''remove key_dynspg_ts / key_dynspg_exp''' (add namelist variables instead) {{{ !----------------------------------------------------------------------- &namdyn_spg ! surface pressure gradient !----------------------------------------------------------------------- ln_dynspg_exp = .false. ! explicit free surface ln_dynspg_ts = .true. ! split-explicit free surface / }}} 4) '''Reviewed AGRIF code in the case of explicit free surface''': slight changes in agrif_opa_interp module, but otherwise ok (quickly tested in ORCA2 Agulhas configuration) ==> Commit changes to revision: 5902 https://forge.ipsl.jussieu.fr/nemo/changeset?old_path=%2Fbranches%2F2015%2Fdev_r5847_MERCATOR9_solveur_simplification&old=5869&new_path=%2Fbranches%2F2015%2Fdev_r5847_MERCATOR9_solveur_simplification&new=5902 '''Step 4: Gurvan's Review:''' GM: change in namelist : regroup namdyn_spg and namsplit namelists + change in some names (ln_bt_nn_auto becomes ln_bt_auto) : {{{ !----------------------------------------------------------------------- &namdyn_spg ! surface pressure gradient computation !----------------------------------------------------------------------- ln_dynspg_exp = .FALSE. ! explicit free surface ln_dynspg_ts = .FALSE. ! split-explicit free surface ln_bt_fw = .TRUE. ! Forward integration of barotropic Eqs. ln_bt_av = .TRUE. ! Time filtering of barotropic variables nn_bt_flt = 1 ! Time filter choice = 0 None ! ! = 1 Boxcar over nn_baro sub-steps ! ! = 2 Boxcar over 2*nn_baro " " ln_bt_auto = .TRUE. ! number of sub-step defined from: rn_bt_cmax = 0.8 ! =T : the Maximum Courant Number allowed nn_baro = 30 ! =F : the number of sub-step in rn_rdt seconds / }}} Note that ln_dynspg_exp = ln_dynspg_ts = .FALSE. in the ref namelist so that this namelist should be systematical fill up in cfg namelist. == '''JC => DONE''' == GM: I don't understand the difference between nn_bt_flt=0 and ln_bt_av=F ....??? == '''JC => Small difference: with nn_bt_flt=0 there is still a specific startup of the barotropic loop, previous bt arrays being not saved.''' == GM: Note that array of time-splitting part should only be allocated if ln_dynspg_ts=TRUE == '''JC => DONE. ''' == GM: dynspg_exp should be modified so that it return the after velocity as dynspg_ts ===>>> simplify dynnxt.F90 == '''JC => No. dynzdf returns velocities and dynspg_ts still returns tendencies: compliant with tracers, and dynzdf must be called at the end (all tendencies must be known because of possible implicit bottom friction) ''' == !GM:dynspg_oce should be suppressed : all variables should be declared either in dynspg.F90 (ln_dynspg_exp and ln_dynspg_ts) or in dynspg_ts for the others == '''JC => DONE. But time splitting arrays are defined in oce.F90 to avoid cyclic dependencies (this is linked to agrif bcs).''' == GM: Step.F90 further simplification are needed here : with removal of solver the DYNAMICS should always be called first ! even in case of explicit free surface !!!!! == '''JC => DONE''' == GM: The only 2 differences is that in explicit free surface un,vn are not updated after the dynamics, and domvvl is called before the dynamics instead of after the dynamics (or in-between if you don’t follow the remark just below) == '''JC => ??''' == GM: why splitting the Dynamics in two parts? make the approximation dz(Ua) computed with e3uw_n ? to be tested … == '''JC => dynamics is not splitted anymore. Yes, one could use "now" vertical scale factors. This approximation has to be tested. ''' == Furthermore, you can notice that ua,va are no more used as workspace in the tracers, ua_sv and va_sn are no more needed , no? == '''JC => ua_sv, va_sv have been suppressed''' == ==> Commit changes to revision: ???[[BR]] '''==> Passes Sette [tests:? tests: ?]??''' [[BR]]'''Step 5: Remaining things to do:''' * Correct momentum trend computation with time splitting (Gurvan 2016 dvpt) * Remove filtered free surface from documentation