Help Needed: Setting Lateral Boundary Conditions in ROMS Model

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hyc006 · #1 Unread post by **hyc006** » Fri Jan 26, 2024 10:15 pm

Hello, I'm a newcomer to ROMS and currently learning the basics of setting up ROMS. I apologize for posing what might be considered a fundamental question. As I work on creating my roms_model.in file based on the roms_upwelling.in test cases, I've encountered a challenge with the lateral boundary conditions section.

In the .in file, I observe two sections for setting the lateral boundary conditions, each corresponding to different boundary condition types:

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!   Keyword    Lateral Boundary Condition Type
!
!   Cha        Chapman
!   Cla        Clamped
!   Clo        Closed
!   Fla        Flather                                _____N_____     j=Mm
!   Gra        Gradient                              |     4     |
!   Nes        Nested                                |           |
!   Nud        Nudging                             1 W           E 3
!   Per        Periodic                              |           |
!   Rad        Radiation                             |_____S_____|
!   Red        Reduced Physics                             2          j=1
!                                                   i=1         i=Lm
!                   W       S       E       N
!                   e       o       a       o
!                   s       u       s       r
!                   t       t       t       t
!                           h               h
!
!                   1       2       3       4

   LBC(isFsur) ==   Per     Clo     Per     Clo         ! free-surface
   LBC(isUbar) ==   Per     Clo     Per     Clo         ! 2D U-momentum
   LBC(isVbar) ==   Per     Clo     Per     Clo         ! 2D V-momentum
   LBC(isUvel) ==   Per     Clo     Per     Clo         ! 3D U-momentum
   LBC(isVvel) ==   Per     Clo     Per     Clo         ! 3D V-momentum
   LBC(isMtke) ==   Per     Clo     Per     Clo         ! mixing TKE

   LBC(isTvar) ==   Per     Clo     Per     Clo \       ! temperature
                    Per     Clo     Per     Clo         ! salinity

In addition, with lateral open boundary edge volume conservation switch for nonlinear model and adjoint-based algorithm:

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  VolCons(west)  ==  F                            ! western  boundary
   VolCons(east)  ==  F                            ! eastern  boundary
   VolCons(south) ==  F                            ! southern boundary
   VolCons(north) ==  F                            ! northern boundary

There's also a place for me to input lateral boundary conditions and climatology file names:

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     BRYNAME == roms_bry.nc               ! Open boundary conditions
     CLMNAME == roms_clm.nc               ! Climatology

Now, I aim to set periodic boundary conditions on the east and west edges, and Chapman & Shchepetkin conditions on the north and south edges. Additionally, I'd like to impose a fixed surface tilt on the north-south edges to drive the flow in the model.

Does this imply that I need to modify the boundary condition section (LBC(isFsur), LBC(isUbar), etc.) to reflect the desired boundary conditions? Also, should I provide a boundary condition file containing the fixed surface tilt for the north-south edges with a NETCDF file specified for "BRYNAME == roms_bry.nc"?

Thank you for your guidance.