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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 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 contains a set of modified files in the classic "MY_SRC" folder to be added in NEMO configuration.

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).

A modified fortran data structure of namtrc was here developed to set the different boundary conditions of passive tracers, as in the following example :

!-----------------------------------------------------------------------
&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.

...
/

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)