# Skilled (#3) - [BDY] &nambdy options and CFL (#49) - Message List

[BDY] &nambdy options and CFL
unsolved

Dear all,

i am trying to model SSH in the Adriatic Sea using a (1/72 deg x 1/72 deg) Adriatic setup of NEMO with a barotropic forcing of SSH/ubar/vbar at the open boundary in the Ionian sea. Tidal harmonic forcing at the boundary is also applied. I use Flather boundary condition for all barotropic dynamics. The model finishes normally if nn_dyn2d_dta = 1 (external barotropic forcing without tidal harmonic forcing) or nn_dyn2d_dta = 2 (tidal harmonic forcing without external barotropic forcing).

However, it blows up quickly if nn_dyn2d_dta = 3. If I understand correctly, this option is a superposition of both forcings above. Is this not true? Is there any aspect of this interaction between tidal and external boundary conditions that i need to pay attention to?

Boundary forcing files seem to be completely consistent with the AMM12 /bdydta/* examples. Nevertheless it seems NaNs start entering the domain at the open boundary in case nn_dyn2d_dta = 3 (see attached image below). If anyone can help me out, i'd be very grateful. This is quite frustrating.

Best regards,

Matjaz

Our CPP keys:

``` bld::tool::fppkeys  key_bdy key_tide key_dynspg_ts key_ldfslp  key_zdfgls  key_vvl key_diainstant key_mpp_mpi key_iomput key_vectopt_loop
```

The relevant (i assume) part of namelist_cfg:

```  ln_tide_pot=.false. clname(1)     =   'Q1'   !  name of constituent clname(2)     =   'O1' clname(3)     =   'P1' clname(4)     =   'S2' clname(5)     =   'K1' clname(6)     =   'K2' clname(7)     =   'N2' clname(8)     =   'M2'

/ !----------------------------------------------------------------------- &nambdy        !  unstructured open boundaries              ("key_bdy") !-----------------------------------------------------------------------

nb_bdy         =  1            !  number of open boundary sets

ln_coords_file = .false.               !  =T : read bdy coordinates from file

cn_dyn2d       = 'flather'            !

nn_dyn2d_dta   =  2          !  = 0, bdy data are equal to the initial state
!  = 1, bdy data are read in 'bdydata   .nc' files !  = 2, use tidal harmonic forcing data from files !  = 3, use external data AND tidal harmonic forcing
cn_dyn3d      =  'none'                ! nn_dyn3d_dta  =  1                    !  = 0, bdy data are equal to the initial state
!  = 1, bdy data are read in 'bdydata   .nc' files
cn_tra        =  'frs'                ! flow relaxation scheme nn_tra_dta    =  1                    !  = 0, bdy data are equal to the initial state
!  = 1, bdy data are read in 'bdydata   .nc' files
cn_ice_lim      =  'none'             ! nn_ice_lim_dta  =  0                  !  = 0, bdy data are equal to the initial state
!  = 1, bdy data are read in 'bdydata   .nc' files
ln_tra_dmp    =.false.                !  open boudaries conditions for tracers ln_dyn3d_dmp  =.false.                !  open boundary condition for baroclinic velocities
rn_time_dmp   =  0.5                   ! Damping time scale in days
rn_time_dmp_out =  0.1                 ! Outflow damping time scale nn_rimwidth   = 10                 !  width of the relaxation zone ln_vol        = .false.               !  total volume correction (see nn_volctl parameter) nn_volctl     = 1                     !  = 0, the total water flux across open boundaries is zero

/ !----------------------------------------------------------------------- &nambdy_index    !  open boundaries - definition           ("key_bdy") !-----------------------------------------------------------------------

ctypebdy = 'S' nbdyind   = -1     ! i-index for segment (>=2 or = -1) nbdybeg   = 2   ! j-index for segment beginning (>=2) nbdyend   = 646  ! j-index for segment end (<= N -1)

/ !----------------------------------------------------------------------- &nambdy_dta      !  open boundaries - external data           ("key_bdy") !----------------------------------------------------------------------- !          !  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      !

bn_ssh =     'NEMOec_bdyH' ,         1        , 'sossheig' ,     .false.     , .false. ,  'daily'  ,    !''      ,   !''    , !''  bn_u2d =     'NEMOec_bdyU_2d' ,      1        , 'vobtcrtx' ,     .false.     , .false. ,  'daily'  ,    !''      ,   !''    , !''  bn_v2d =     'NEMOec_bdyV_2d' ,      1       , 'vobtcrty' ,     .false.     , .false. ,  'daily'  ,    !''      ,   !''    , !''  bn_u3d  =    'NEMOec_bdyU_3d' ,      1        , 'vozocrtx' ,     .false.     , .false. ,  'daily'  ,    !''      ,   !''    , !''  bn_v3d  =    'NEMOec_bdyV_3d' ,      1        , 'vomecrty' ,     .false.     , .false. ,  'daily'  ,    !''      ,   !''    , !''  bn_tem  =    'NEMOec_bdyT'   ,       24        , 'votemper' ,     .false.     , .false. ,  'daily'  ,    !''      ,   !''    , !''  bn_sal  =    'NEMOec_bdyS'   ,       24        , 'vosaline' ,     .false.     , .false. ,  'daily'  ,    !''      ,   !''    , !''  cn_dir  =    '../bdy/' ln_full_vel = .false.      ! =T => full velocities in 3D boundary data
! =F => baroclinic velocities in 3D boundary data

/ !----------------------------------------------------------------------- &nambdy_tide     ! tidal forcing at open boundaries !-----------------------------------------------------------------------

filtide      = '../bdy/NEMOec_bdytide_'        !  file name root of tidal forcing files

/ }}}
```
• Message #83

Hi Matjaz,

Please consider attaching your namelist file in the subject because the lines displayed are quite unreadable now.

Then you can integrate your image in the discussion thread with [[Image(...)]] wiki macro.

Regards,
Nicolas