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NEMO v3.6 TOP BDY Patch

Last edition: Wikinfo(changed_ts)? by Wikinfo(changed_by)?

BEFORE USE : this patch is meant to provide only the core functionality for TOP BDY. Official support for tracers BDY will be given only for versions after NEMO v4.0.

Description

This patch to enable the core support of BDY for TOP passive tracers with NEMO v3.6 (tested with r10254). Note that in this patch, routines that provide to initialization/reading of all Boundary conditions (trcbc.f90) were also updated.

BDY schemes included in this version are the following (see trcbdy.F90):

• frs : Flow Relaxation Scheme
• specified : Specified value
• neumann : Duplicate the value for tracers
• orlanski : Orlanski radiation
• orlanski_npo : Orlanski radiation with adaptive nudging

Refer to the BDY description of NEMO manual for further details on the different schemes.

In namelist_top_ref the following changes are necessary (see the patched version contained in the code provided):

 !-----------------------------------------------------------------------
 &namtrc_bc
 !
   cn_dir_sbc        =  './'      !  root directory for the location of SURFACE data files
   cn_dir_cbc        =  './'      !  root directory for the location of COASTAL data files
   cn_dir_obc        =  './'      !  root directory for the location of OPEN data files
/
!----------------------------------------------------------------------
!namtrc_bdy       !   Setup of tracer boundary conditions
!-----------------------------------------------------------------------
$namtrc_bdy
   cn_trc_dflt     =  'neumann'    !  OBC applied by default to all tracers
   cn_trc          =  'none'       !  Boundary conditions applied to the passive tracers (selected in namtrc)

   nn_trcdmp_bdy   = 0     !  Use damping timescales defined in nambdy of namelist
                           !  = 0 NO damping of tracers at open boudaries
                           !  = 1 Only for tracers forced with external data
                           !  = 2 Damping applied to all tracers
 /

Details on the usage of these namelists and the setup of a one tracer case are given below.

Usage walktrough

Code is contained in the attached tarball and it consists of modified files wrapped in the classic "MY_SRC" folder to be added in NEMO configuration. These files have to be unpacked in the MY_SRC folder of your configuration in order to be used.

REMINDER: MY_SRC contains user modified versions of NEMO routines or new pieces of code that are used at compilation time to supersede at original ones.

Note that namelist_top_ref has to be modified by the user in <NEMODIR>/NEMOGCM/CONFIG/SHARED according to the description above (or the sample file provided in the tarball).

All boundary conditions are controlled within the namelist namtrc in namelist_top_(cfg/ref). A modified fortran data structure of namtrc was here developed to set the different boundary conditions of passive tracers, as in the following example of namelist_top_cfg :

!-----------------------------------------------------------------------
&namtrc     !   tracers definition
!-----------------------------------------------------------------------
!                !    name   !           title of the field              ! initial data ! initial data !   sbc   !   cbc   !   obc   ! save   !
!                !           !                                           !  units       ! from file    !         !         !         ! or not !
!                !           !                                           !              ! or not       !         !         !         !        !
   sn_tracer(1)   = 'TRACER1  ' , 'Tracer1 for key_my_trc               ',  'unitless'  ,   .true.     , .false. , .true.  , .true.  ,  .true.

...
/

where the new options relates to the provision of SURFACE (sbc), COASTAL (cbc), or OPEN lateral Boundaries (obc) data for sn_tracer(1) named TRACER1.

In namtrc_bc are provided the different boundary conditions for passive tracers, see the example below of namelist_top_cfg

!----------------------------------------------------------------------
&namtrc_bc        !   data for boundary conditions
!-----------------------------------------------------------------------
!                !  file name               ! frequency (hours) ! variable  ! time interp. !  clim  ! 'yearly'/ ! weights  ! rotation ! land/sea mask !
!                !                          !  (if <0  months)  !   name    !   (logical)  !  (T/F) ! 'monthly' ! filename ! pairing  ! filename      !
   sn_trcsbc(1)  = 'TRACER_SBC'        ,        -12        ,  'TRACER_SUR'     ,    .false.   , .true. , 'yearly'  , ''       , ''   , ''
   rn_trsfac(1)  = 1.0
   sn_trccbc(1)  = 'TRACER_CBC'        ,        -12        ,  'TRACER_RIV'     ,    .false.   , .true. , 'yearly'  , ''       , ''   , ''
   rn_trcfac(1)  = 1.0
   sn_trcobc(1)  = 'TRACER_BDY'        ,        -12        ,  'TRACER_BDY'     ,    .false.   , .true. , 'yearly'  , ''       , ''   , ''
   rn_trofac(1)  = 1.0
   !
   cn_dir_sbc        =  './'      !  root directory for the location of SURFACE data files
   cn_dir_cbc        =  './'      !  root directory for the location of COASTAL data files
   cn_dir_obc        =  './'      !  root directory for the location of OPEN data files
/

Input files are provided using the standard NEMO fldread structure and follow the convention sn_trcsbc = surface, sn_trccbc = coastal, sn_trcobc = open lateral, with the correspondig scaling factors rn_trsfac = surface, rn_trcfac = coastal, rn_trofac = open lateral.

namtrc_bc : here are provided the different boundary conditions for passive tracers, namely surface, coastal, and open lateral boundaries (see the example below for usage). namtrc_bdy : here set the BDY schemes to be used for those tracers that BDY inputs are provided (according to namtrc options)