Changes between Version 4 and Version 5 of ticket/0663_MLF
 Timestamp:
 20100422T19:42:48+02:00 (11 years ago)
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ticket/0663_MLF
v4 v5 24 24 This update is part of the LOCEAN.8 task (Update of the ocean physics) due by June 25th 2010. 25 25 26 The main remainingmodifications concern :26 The 3 main modifications concern : 27 27 28 (1) forcing termsas a mean between time step n1/2 and n+1/2 (sbcmod.F90, sbc.F90, trasbc.F90, dynzdf....F90)28 '''(1) The forcing terms'''. They are defined as a mean between time step n1/2 and n+1/2 (sbcmod.F90, sbc.F90, trasbc.F90, dynzdf....F90) 29 29 30 30 [[Image(NEW_LF_RA.jpg, 50%)]][[BR]] … … 38 38 Beginning of sbs routine, introduce the swap, but only for kt >= nit000+1. If no restart, the '_b' fields is known only at the end of the sbc calculation. Therefore we have choosen to regroup the setting of '_b' fields at nit000 at the end of sbc routine. CAUTION : here the swap must be done at each kt, what ever the nn_fsbc value is. Otherwise the ocean forcing will be wrong. 39 39 40 (2) Asselin filter:remove the forcing from the filter (dynnxt (?), tranxt, traqsr)40 '''(2) The Asselin filter''' remove the forcing from the filter (dynnxt (?), tranxt, traqsr) 41 41 42 (3) tranxt.F90 : semiimplicit hydrostatic pressure gradient : change the coefficientsto take into account the Asselin filter parameter42 '''(3) The semiimplicit hpg'''. In tranxt.F90, for the semiimplicit hydrostatic pressure gradient, the coefficients are changed in order to take into account the Asselin filter parameter 43 43 44 44 time mean T and S for the semi implicit hpg computation was (ta+2*tn + tb) / 4 . It is now replaced by … … 50 50 The change extend further the stability limit of the time stepping scheme when ln_dynhpg_imp = T 51 51 52 '''N.B.''' : Three key elements of the LFRA scheme have already been implemented in former version of NEMO (v3.0 and v3.1). As a remainder, there are: 52 53 53 === Open questions === 54 Forcing evaluation : the momentum and tracers forcing are evaluated at kt+1/2, nomore at kt. This is done in the fldread routine since v3.0 55 Flow chart : general structure has changed for key_vvl (variable volume or equivalently nonlinear free surface) (v3.1). In particular the ssh equation is solved first together followed immediately by the computation of the now vertical velocity, so that wn is available to solve the tracer and the dynamics equations. 54 56 55 (2) Do we need to remove the stress component from the filter in dynnxt? 57 The enhanced vertical diffusion (evd) is no more a source of small divergence of two consecutive time step as the static instability is now tested on both before and now fields. See ticket #401. 56 58 57 (3) in vvl case : thickness weighted tracer in the time mean, do we need to compute and use a time mean thickness in the hpg computation? 59 60 === Pending issues === 61 62 • Do we need to remove the stress component from the filter in dynnxt? 63 64 • in vvl case : thickness weighted tracer in the time mean, do we need to compute and use a time mean thickness in the hpg computation? 65 66 • The associated changes in TOP are still unclear. A priori, in PISCES p4zopt.F90 should be modified. Nevertheless, the TOP time stepping strategy seems to be a forward in time scheme. If yes, then the evaluation of the forcing at kt+1/2 is an improvement (if not to say a bug fix!). If not, action is required... 67 68 69 • Check the consistency with the change planned in the emps field (switch to fsalt, a true salt flux). 70 71 72 • modification required in limsbc, limsbc_2 and CICE interface : conversion of emps into a salt flux (new name 'fsalt' ?) 73 74 75 • the modifications in trasbc will interfere with the new runoff scheme (see 2009WP/2009Stream3#Substream3.2:fromNEMOteamshortterm) 58 76 59 77 