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New TIDAL_SAL_FLATHER option
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  - This option is defaulted to False to retain previous answers,
    but should be set to True for new experiments in order to make
    the Flather OBC routine consistent with the barotropic solver
  - This option only applies for regional OBC cases with Tides and
    scalar self-attraction and loading
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@MJHarrison-GFDL
MJHarrison-GFDL committed Jul 13, 2023
1 parent 7970347 commit 8d83f42
Showing 1 changed file with 27 additions and 6 deletions.
33 changes: 27 additions & 6 deletions src/core/MOM_barotropic.F90
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Original file line number Diff line number Diff line change
Expand Up @@ -273,6 +273,9 @@ module MOM_barotropic
logical :: use_old_coriolis_bracket_bug !< If True, use an order of operations
!! that is not bitwise rotationally symmetric in the
!! meridional Coriolis term of the barotropic solver.
logical :: tidal_sal_flather !< Apply adjustment to external gravity wave speed
!! consistent with tidal self-attraction and loading
!! used within the barotropic solver
type(time_type), pointer :: Time => NULL() !< A pointer to the ocean models clock.
type(diag_ctrl), pointer :: diag => NULL() !< A structure that is used to regulate
!! the timing of diagnostic output.
Expand Down Expand Up @@ -1118,8 +1121,13 @@ subroutine btstep(U_in, V_in, eta_in, dt, bc_accel_u, bc_accel_v, forces, pbce,

! Set up fields related to the open boundary conditions.
if (apply_OBCs) then
call set_up_BT_OBC(OBC, eta, CS%BT_OBC, CS%BT_Domain, G, GV, US, MS, ievf-ie, use_BT_cont, &
integral_BT_cont, dt, Datu, Datv, BTCL_u, BTCL_v)
if (CS%tides .and. CS%TIDAL_SAL_FLATHER) then
call set_up_BT_OBC(OBC, eta, CS%BT_OBC, CS%BT_Domain, G, GV, US, MS, ievf-ie, use_BT_cont, &
integral_BT_cont, dt, Datu, Datv, BTCL_u, BTCL_v, dgeo_de)
else
call set_up_BT_OBC(OBC, eta, CS%BT_OBC, CS%BT_Domain, G, GV, US, MS, ievf-ie, use_BT_cont, &
integral_BT_cont, dt, Datu, Datv, BTCL_u, BTCL_v)
endif
endif

! Determine the difference between the sum of the layer fluxes and the
Expand Down Expand Up @@ -3083,7 +3091,7 @@ end subroutine apply_velocity_OBCs
!> This subroutine sets up the private structure used to apply the open
!! boundary conditions, as developed by Mehmet Ilicak.
subroutine set_up_BT_OBC(OBC, eta, BT_OBC, BT_Domain, G, GV, US, MS, halo, use_BT_cont, &
integral_BT_cont, dt_baroclinic, Datu, Datv, BTCL_u, BTCL_v)
integral_BT_cont, dt_baroclinic, Datu, Datv, BTCL_u, BTCL_v, dgeo_de)
type(ocean_OBC_type), target, intent(inout) :: OBC !< An associated pointer to an OBC type.
type(memory_size_type), intent(in) :: MS !< A type that describes the memory sizes of the
!! argument arrays.
Expand Down Expand Up @@ -3114,9 +3122,11 @@ subroutine set_up_BT_OBC(OBC, eta, BT_OBC, BT_Domain, G, GV, US, MS, halo, use_B
type(local_BT_cont_v_type), dimension(SZIW_(MS),SZJBW_(MS)), intent(in) :: BTCL_v !< Structure of information used
!! for a dynamic estimate of the face areas at
!! v-points.

real, intent(in), optional :: dgeo_de !< The constant of proportionality between
!! geopotential and sea surface height [nondim].
! Local variables
real :: I_dt ! The inverse of the time interval of this call [T-1 ~> s-1].
real :: dgeo_de_in !< The constant of proportionality between geopotential and sea surface height [nondim].
integer :: i, j, k, is, ie, js, je, n, nz
integer :: isd, ied, jsd, jed, IsdB, IedB, JsdB, JedB
integer :: isdw, iedw, jsdw, jedw
Expand All @@ -3134,6 +3144,9 @@ subroutine set_up_BT_OBC(OBC, eta, BT_OBC, BT_Domain, G, GV, US, MS, halo, use_B
"yet fully implemented with wide barotropic halos.")
endif

dgeo_de_in = 1.0
if (PRESENT(dgeo_de)) dgeo_de_in = dgeo_de

if (.not. BT_OBC%is_alloced) then
allocate(BT_OBC%Cg_u(isdw-1:iedw,jsdw:jedw), source=0.0)
allocate(BT_OBC%H_u(isdw-1:iedw,jsdw:jedw), source=0.0)
Expand Down Expand Up @@ -3192,7 +3205,7 @@ subroutine set_up_BT_OBC(OBC, eta, BT_OBC, BT_Domain, G, GV, US, MS, halo, use_B
BT_OBC%H_u(I,j) = eta(i+1,j)
endif
endif
BT_OBC%Cg_u(I,j) = SQRT(GV%g_prime(1) * GV%H_to_Z*BT_OBC%H_u(i,j))
BT_OBC%Cg_u(I,j) = SQRT(dgeo_de_in * GV%g_prime(1) * GV%H_to_Z*BT_OBC%H_u(i,j))
endif
endif ; enddo ; enddo
if (OBC%Flather_u_BCs_exist_globally) then
Expand Down Expand Up @@ -3246,7 +3259,7 @@ subroutine set_up_BT_OBC(OBC, eta, BT_OBC, BT_Domain, G, GV, US, MS, halo, use_B
BT_OBC%H_v(i,J) = eta(i,j+1)
endif
endif
BT_OBC%Cg_v(i,J) = SQRT(GV%g_prime(1) * GV%H_to_Z*BT_OBC%H_v(i,J))
BT_OBC%Cg_v(i,J) = SQRT(dgeo_de_in * GV%g_prime(1) * GV%H_to_Z*BT_OBC%H_v(i,J))
endif
endif ; enddo ; enddo
if (OBC%Flather_v_BCs_exist_globally) then
Expand Down Expand Up @@ -4496,6 +4509,14 @@ subroutine barotropic_init(u, v, h, eta, Time, G, GV, US, param_file, diag, CS,
"solver has the wrong sign, replicating a long-standing bug with a scalar "//&
"self-attraction and loading term or the SAL term from a previous simulation.", &
default=.false., do_not_log=(det_de==0.0))
call get_param(param_file, mdl, "TIDAL_SAL_FLATHER", CS%tidal_sal_flather, &
"If true, then apply adjustments to the external gravity "//&
"wave speed used with the Flather OBC routine consistent "//&
"with the barotropic solver. This applies to cases with "//&
"tidal forcing using the scalar self-attraction approximation. "//&
"The default is currently False in order to retain previous answers "//&
"but should be set to True for new experiments", default=.false.)

call get_param(param_file, mdl, "SADOURNY", CS%Sadourny, &
"If true, the Coriolis terms are discretized with the "//&
"Sadourny (1975) energy conserving scheme, otherwise "//&
Expand Down

1 comment on commit 8d83f42

@kshedstrom
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I would check the parameter in the OBC part of the code so that it shows up in the OBC part of the parameter_docs. Or do you not have the right information in the right place that way?

If this is a bug fix, shouldn't the name of it be TIDAL_SAL_FLATHER_ANSWER_DATE with a default of 99991231?

Another person who is potentially interested in this is @andrew-c-ross

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