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Frequency-dependent drag in tensor form #978

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63 changes: 54 additions & 9 deletions src/parameterizations/lateral/MOM_wave_drag.F90
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,10 @@ module MOM_wave_drag
integer :: nf !< Number of filters to be used in the simulation
real, allocatable, dimension(:,:,:) :: coef_u !< frequency-dependent drag coefficients [H T-1 ~> m s-1]
real, allocatable, dimension(:,:,:) :: coef_v !< frequency-dependent drag coefficients [H T-1 ~> m s-1]
real, allocatable, dimension(:,:,:) :: coef_uv !< frequency-dependent drag coefficients [H T-1 ~> m s-1]
real, allocatable, dimension(:,:,:) :: coef_vu !< frequency-dependent drag coefficients [H T-1 ~> m s-1]
logical :: tensor_drag !< If true, include the off-diagonal components of the
!! wave drag tensor for computing the wave drag
end type wave_drag_CS

contains
Expand All @@ -38,7 +42,7 @@ subroutine wave_drag_init(param_file, wave_drag_file, G, GV, US, CS)
character(len=40) :: mdl = "MOM_wave_drag" !< This module's name
character(len=50) :: filter_name_str !< List of drag coefficients to be used
character(len=2), allocatable, dimension(:) :: filter_names !< Names of drag coefficients
character(len=80) :: var_names(2) !< Names of variables in wave_drag_file
character(len=80) :: var_names(4) !< Names of variables in wave_drag_file
character(len=200) :: mesg
real :: var_scale !< Scaling factors of drag coefficients [nondim]
integer :: c
Expand All @@ -53,8 +57,12 @@ subroutine wave_drag_init(param_file, wave_drag_file, G, GV, US, CS)

allocate(CS%coef_u(G%IsdB:G%IedB,G%jsd:G%jed,CS%nf)) ; CS%coef_u(:,:,:) = 0.0
allocate(CS%coef_v(G%isd:G%ied,G%JsdB:G%JedB,CS%nf)) ; CS%coef_v(:,:,:) = 0.0
allocate(CS%coef_uv(G%IsdB:G%IedB,G%jsd:G%jed,CS%nf)) ; CS%coef_uv(:,:,:) = 0.0
allocate(CS%coef_vu(G%isd:G%ied,G%JsdB:G%JedB,CS%nf)) ; CS%coef_vu(:,:,:) = 0.0
allocate(filter_names(CS%nf)) ; read(filter_name_str, *) filter_names

CS%tensor_drag = .false.

if (len_trim(wave_drag_file) > 0) then
do c=1,CS%nf
call get_param(param_file, mdl, "BT_"//trim(filter_names(c))//"_DRAG_U", &
Expand All @@ -65,18 +73,39 @@ subroutine wave_drag_init(param_file, wave_drag_file, G, GV, US, CS)
var_names(2), "The name of the variable in BT_WAVE_DRAG_FILE "//&
"for the drag coefficient of the "//trim(filter_names(c))//&
" frequency at v points.", default="")
call get_param(param_file, mdl, "BT_"//trim(filter_names(c))//"_DRAG_UV", &
var_names(3), "The name of the variable in BT_WAVE_DRAG_FILE "//&
"for the drag coefficient of the "//trim(filter_names(c))//&
" frequency at u points, corresponding to the off-diagonal "//&
"component of the wave drag tensor.", default="")
call get_param(param_file, mdl, "BT_"//trim(filter_names(c))//"_DRAG_VU", &
var_names(4), "The name of the variable in BT_WAVE_DRAG_FILE "//&
"for the drag coefficient of the "//trim(filter_names(c))//&
" frequency at v points, corresponding to the off-diagonal "//&
"component of the wave drag tensor.", default="")
call get_param(param_file, mdl, "BT_"//trim(filter_names(c))//"_DRAG_SCALE", &
var_scale, "A scaling factor for the drag coefficient of the "//&
trim(filter_names(c))//" frequency.", default=1.0, units="nondim")

if (len_trim(var_names(1))+len_trim(var_names(2))>0 .and. var_scale>0.0) then
if (len_trim(var_names(1))>0 .and. len_trim(var_names(2))>0 .and. var_scale>0.0) then
call MOM_read_data(wave_drag_file, trim(var_names(1)), CS%coef_u(:,:,c), G%Domain, &
position=EAST_FACE, scale=var_scale*GV%m_to_H*US%T_to_s)
call MOM_read_data(wave_drag_file, trim(var_names(2)), CS%coef_v(:,:,c), G%Domain, &
position=NORTH_FACE, scale=var_scale*GV%m_to_H*US%T_to_s)
call pass_vector(CS%coef_u(:,:,c), CS%coef_v(:,:,c), G%domain, &
direction=To_All+SCALAR_PAIR)

if (len_trim(var_names(3))>0 .and. len_trim(var_names(4))>0) then
CS%tensor_drag = .true.

call MOM_read_data(wave_drag_file, trim(var_names(3)), CS%coef_uv(:,:,c), G%Domain, &
position=EAST_FACE, scale=var_scale*GV%m_to_H*US%T_to_s)
call MOM_read_data(wave_drag_file, trim(var_names(4)), CS%coef_vu(:,:,c), G%Domain, &
position=NORTH_FACE, scale=var_scale*GV%m_to_H*US%T_to_s)
call pass_vector(CS%coef_uv(:,:,c), CS%coef_vu(:,:,c), G%domain, &
direction=To_All+SCALAR_PAIR)
endif

write(mesg, *) "MOM_wave_drag: ", trim(filter_names(c)), &
" coefficients read from file, scaling factor = ", var_scale
call MOM_error(NOTE, trim(mesg))
Expand Down Expand Up @@ -105,17 +134,33 @@ subroutine wave_drag_calc(u, v, drag_u, drag_v, G, CS)

is = G%isc ; ie = G%iec ; js = G%jsc ; je = G%jec

Drag_u(:,:) = 0.0 ; Drag_v(:,:) = 0.0
drag_u(:,:) = 0.0 ; drag_v(:,:) = 0.0

if (CS%tensor_drag) then
do k=1,CS%nf
call pass_vector(u(:,:,k), v(:,:,k), G%domain, direction=To_All+SCALAR_PAIR)
enddo
endif

!$OMP do
do k=1,CS%nf ; do j=js,je ; do I=is-1,ie
Drag_u(I,j) = Drag_u(I,j) + u(I,j,k) * CS%coef_u(I,j,k)
enddo ; enddo ; enddo
do j=js,je ; do I=is-1,ie ; do k=1,CS%nf ; if (G%mask2dCu(I,j) * CS%coef_u(I,j,k) > 0.0) then
drag_u(I,j) = drag_u(I,j) + u(I,j,k) * CS%coef_u(I,j,k)

if (CS%tensor_drag) then
drag_u(I,j) = drag_u(I,j) + &
0.25 * ((v(i+1,J,k) + v(i,J-1,k)) + (v(i,J,k) + v(i+1,J-1,k))) * CS%coef_uv(I,j,k)
endif
endif ; enddo ; enddo ; enddo

!$OMP do
do k=1,CS%nf ; do J=js-1,je ; do i=is,ie
Drag_v(i,J) = Drag_v(i,J) + v(i,J,k) * CS%coef_v(i,J,k)
enddo ; enddo ; enddo
do J=js-1,je ; do i=is,ie ; do k=1,CS%nf ; if (G%mask2dCv(i,J) * CS%coef_v(i,J,k) > 0.0) then
drag_v(i,J) = drag_v(i,J) + v(i,J,k) * CS%coef_v(i,J,k)

if (CS%tensor_drag) then
drag_v(i,J) = drag_v(i,J) + &
0.25 * ((u(I-1,j,k) + u(I,j+1,k)) + (u(I,j,k) + u(I-1,j+1,k))) * CS%coef_vu(i,J,k)
endif
endif ; enddo ; enddo ; enddo

end subroutine wave_drag_calc

Expand Down