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Nodal modulation #725

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Nodal modulation #725

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211cab5
Nodal modulation
c2xu Sep 6, 2024
405213a
Merge branch 'NOAA-GFDL:dev/gfdl' into c2xu/nodal_modulation
c2xu Sep 14, 2024
7a64956
Merge branch 'dev/gfdl' into c2xu/nodal_modulation
Hallberg-NOAA Dec 15, 2024
59211b6
Nodal Modulation
c2xu Dec 16, 2024
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41 changes: 33 additions & 8 deletions src/core/MOM_open_boundary.F90
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Expand Up @@ -1169,26 +1169,51 @@ subroutine initialize_obc_tides(OBC, US, param_file)
type(astro_longitudes) :: nodal_longitudes !< Solar and lunar longitudes for tidal forcing
type(time_type) :: nodal_time !< Model time to calculate nodal modulation for.
integer :: c !< Index to tidal constituent.
logical :: tides !< True if astronomical tides are also used.

call get_param(param_file, mdl, "OBC_TIDE_CONSTITUENTS", tide_constituent_str, &
"Names of tidal constituents being added to the open boundaries.", &
fail_if_missing=.true.)

call get_param(param_file, mdl, "OBC_TIDE_ADD_EQ_PHASE", OBC%add_eq_phase, &
call get_param(param_file, mdl, "TIDES", tides, &
"If true, apply tidal momentum forcing.", default=.false., do_not_log=.true.)

call get_param(param_file, mdl, "TIDE_USE_EQ_PHASE", OBC%add_eq_phase, &
"If true, add the equilibrium phase argument to the specified tidal phases.", &
default=.false., fail_if_missing=.false.)
default=.false., do_not_log=tides)
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call get_param(param_file, mdl, "OBC_TIDE_ADD_NODAL", OBC%add_nodal_terms, &
call get_param(param_file, mdl, "TIDE_ADD_NODAL", OBC%add_nodal_terms, &
"If true, include 18.6 year nodal modulation in the boundary tidal forcing.", &
default=.false.)
default=.false., do_not_log=tides)

call get_param(param_file, mdl, "OBC_TIDE_REF_DATE", tide_ref_date, &
call get_param(param_file, mdl, "TIDE_REF_DATE", tide_ref_date, &
"Reference date to use for tidal calculations and equilibrium phase.", &
fail_if_missing=.true.)
default=0, do_not_log=tides)

call get_param(param_file, mdl, "OBC_TIDE_NODAL_REF_DATE", nodal_ref_date, &
call get_param(param_file, mdl, "TIDE_NODAL_REF_DATE", nodal_ref_date, &
"Fixed reference date to use for nodal modulation of boundary tides.", &
fail_if_missing=.false., default=0)
default=0, do_not_log=tides)

! The following parameters are to be obsolete in the future
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These 4 parameters would need to have default arguments if they are to be properly logged in the correct MOM_parameter_doc files.

It may be that we need to add support for a default array of integers to get_param_integer_array(), analogously to what we recently added for get_param_real_array().

If we were to get community buy-in on the idea of moving to use the non-OBC parameters for these tidal parameters, we might deal with this by storing the values set above, adding do_not_log=.true. to these get_param() calls, and then directly adding a warning if variables like OBC_TIDE_ADD_EQ_PHASE are set differently from TIDE_USE_EQ_PHASE. I will try to raise this at this evening's MOM6 dev call, and then provide further guidance depending on how that conversation goes.

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The default arguments for these parameters are already set by TIDE_USE_EQ_PHASE, TIDE_ADD_NODAL, TIDE_REF_DATE and TIDE_NODAL_REF_DATE, so they will always be properly logged. I've tested this.

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@c2xu c2xu Dec 16, 2024 •
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It would be more complicated if we want to add a warning if the old variables (e.g., OBC_TIDE_ADD_EQ_PHASE) are set differently from the new ones (e.g., TIDE_USE_EQ_PHASE), but I don't think this should happen if both astronomical and OBC tidal forcings are turned on (and this is the reason for obsoleting the old variables). I did not add a do_not_log option because these parameters were used by OBC tidal forcing only, and I think it would be easier to just remind everyone who uses OBC tidal forcing that these parameters will be obsolete.

call get_param(param_file, mdl, "OBC_TIDE_ADD_EQ_PHASE", OBC%add_eq_phase, &
"If true, add the equilibrium phase argument to the specified tidal phases. "//&
"This parameter will be obsolete in the future. Instead use TIDE_USE_EQ_PHASE.", &
fail_if_missing=.false.)

call get_param(param_file, mdl, "OBC_TIDE_ADD_NODAL", OBC%add_nodal_terms, &
"If true, include 18.6 year nodal modulation in the boundary tidal forcing. "//&
"This parameter will be obsolete in the future. Instead use TIDE_ADD_NODAL.", &
fail_if_missing=.false.)

call get_param(param_file, mdl, "OBC_TIDE_REF_DATE", tide_ref_date, &
"Reference date to use for tidal calculations and equilibrium phase. "//&
"This parameter will be obsolete in the future. Instead use TIDE_REF_DATE.", &
fail_if_missing=.false.)

call get_param(param_file, mdl, "OBC_TIDE_NODAL_REF_DATE", nodal_ref_date, &
"Fixed reference date to use for nodal modulation of boundary tides. "//&
"This parameter will be obsolete in the future. Instead use TIDE_NODAL_REF_DATE.", &
fail_if_missing=.false.)

if (.not. OBC%add_eq_phase) then
! If equilibrium phase argument is not added, the input phases
Expand Down
26 changes: 16 additions & 10 deletions src/diagnostics/MOM_harmonic_analysis.F90
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Expand Up @@ -46,7 +46,9 @@ module MOM_harmonic_analysis
time_ref !< Reference time (t = 0) used to calculate tidal forcing
real, dimension(MAX_CONSTITUENTS) :: &
freq, & !< The frequency of a tidal constituent [T-1 ~> s-1]
phase0 !< The phase of a tidal constituent at time 0 [rad]
phase0, & !< The phase of a tidal constituent at time 0 [rad]
tide_fn, & !< Amplitude modulation of tides by nodal cycle [nondim].
tide_un !< Phase modulation of tides by nodal cycle [rad].
real, allocatable :: FtF(:,:) !< Accumulator of (F' * F) for all fields [nondim]
integer :: nc !< The number of tidal constituents in use
integer :: length !< Number of fields of which harmonic analysis is to be performed
Expand All @@ -60,13 +62,15 @@ module MOM_harmonic_analysis

!> This subroutine sets static variables used by this module and initializes CS%list.
!! THIS MUST BE CALLED AT THE END OF tidal_forcing_init.
subroutine HA_init(Time, US, param_file, time_ref, nc, freq, phase0, const_name, CS)
subroutine HA_init(Time, US, param_file, time_ref, nc, freq, phase0, const_name, tide_fn, tide_un, CS)
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type(time_type), intent(in) :: Time !< The current model time
type(time_type), intent(in) :: time_ref !< Reference time (t = 0) used to calculate tidal forcing
type(unit_scale_type), intent(in) :: US !< A dimensional unit scaling type
type(param_file_type), intent(in) :: param_file !< A structure to parse for run-time parameters
real, dimension(MAX_CONSTITUENTS), intent(in) :: freq !< The frequency of a tidal constituent [T-1 ~> s-1]
real, dimension(MAX_CONSTITUENTS), intent(in) :: phase0 !< The phase of a tidal constituent at time 0 [rad]
real, dimension(MAX_CONSTITUENTS), intent(in) :: freq !< The frequency of a tidal constituent [T-1 ~> s-1]
real, dimension(MAX_CONSTITUENTS), intent(in) :: phase0 !< The phase of a tidal constituent at time 0 [rad]
real, dimension(MAX_CONSTITUENTS), intent(in) :: tide_fn !< Amplitude modulation of tides by nodal cycle [nondim].
real, dimension(MAX_CONSTITUENTS), intent(in) :: tide_un !< Phase modulation of tides by nodal cycle [rad].
integer, intent(in) :: nc !< The number of tidal constituents in use
character(len=16), intent(in) :: const_name(MAX_CONSTITUENTS) !< The name of each constituent
type(harmonic_analysis_CS), intent(out) :: CS !< Control structure of the MOM_harmonic_analysis module
Expand Down Expand Up @@ -135,6 +139,8 @@ subroutine HA_init(Time, US, param_file, time_ref, nc, freq, phase0, const_name,
CS%time_ref = time_ref
CS%freq = freq
CS%phase0 = phase0
CS%tide_fn = tide_fn
CS%tide_un = tide_un
CS%nc = nc
CS%const_name = const_name
CS%length = 0
Expand Down Expand Up @@ -198,8 +204,8 @@ subroutine HA_accum_FtF(Time, CS)
do c=1,nc
icos = 2*c
isin = 2*c+1
cosomegat = cos(CS%freq(c) * now + CS%phase0(c))
sinomegat = sin(CS%freq(c) * now + CS%phase0(c))
cosomegat = CS%tide_fn(c) * cos(CS%freq(c) * now + (CS%phase0(c) + CS%tide_un(c)))
sinomegat = CS%tide_fn(c) * sin(CS%freq(c) * now + (CS%phase0(c) + CS%tide_un(c)))

! First column, corresponding to the zero frequency constituent (mean)
CS%FtF(icos,1) = CS%FtF(icos,1) + cosomegat
Expand All @@ -208,8 +214,8 @@ subroutine HA_accum_FtF(Time, CS)
do cc=1,c
iccos = 2*cc
issin = 2*cc+1
ccosomegat = cos(CS%freq(cc) * now + CS%phase0(cc))
ssinomegat = sin(CS%freq(cc) * now + CS%phase0(cc))
ccosomegat = CS%tide_fn(cc) * cos(CS%freq(cc) * now + (CS%phase0(cc) + CS%tide_un(cc)))
ssinomegat = CS%tide_fn(cc) * sin(CS%freq(cc) * now + (CS%phase0(cc) + CS%tide_un(cc)))

! Interior of the matrix, corresponding to the products of cosine and sine terms
CS%FtF(icos,iccos) = CS%FtF(icos,iccos) + cosomegat * ccosomegat
Expand Down Expand Up @@ -290,8 +296,8 @@ subroutine HA_accum_FtSSH(key, data, Time, G, CS)
do c=1,nc
icos = 2*c
isin = 2*c+1
cosomegat = cos(CS%freq(c) * now + CS%phase0(c))
sinomegat = sin(CS%freq(c) * now + CS%phase0(c))
cosomegat = CS%tide_fn(c) * cos(CS%freq(c) * now + (CS%phase0(c) + CS%tide_un(c)))
sinomegat = CS%tide_fn(c) * sin(CS%freq(c) * now + (CS%phase0(c) + CS%tide_un(c)))
do j=js,je ; do i=is,ie
ha1%FtSSH(i,j,icos) = ha1%FtSSH(i,j,icos) + (data(i,j) - ha1%ref(i,j)) * cosomegat
ha1%FtSSH(i,j,isin) = ha1%FtSSH(i,j,isin) + (data(i,j) - ha1%ref(i,j)) * sinomegat
Expand Down
6 changes: 6 additions & 0 deletions src/diagnostics/MOM_obsolete_params.F90
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Expand Up @@ -155,6 +155,12 @@ subroutine find_obsolete_params(param_file)
call obsolete_logical(param_file, "USE_GRID_SPACE_DIAGNOSTIC_AXES", &
hint="Instead use USE_INDEX_DIAGNOSTIC_AXIS.")

! These parameters will be obsolete in the future
! call obsolete_logical(param_file, "OBC_TIDE_ADD_EQ_PHASE", hint="Instead use TIDE_USE_EQ_PHASE.")
! call obsolete_logical(param_file, "OBC_TIDE_ADD_NODAL", hint="Instead use TIDE_ADD_NODAL.")
! call obsolete_int(param_file, "OBC_TIDE_REF_DATE", hint="Instead use TIDE_REF_DATE.")
! call obsolete_int(param_file, "OBC_TIDE_NODAL_REF_DATE", hint="Instead use TIDE_NODAL_REF_DATE.")

! Write the file version number to the model log.
call log_version(param_file, mdl, version)

Expand Down
73 changes: 59 additions & 14 deletions src/parameterizations/lateral/MOM_tidal_forcing.F90
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Expand Up @@ -70,7 +70,9 @@ module MOM_tidal_forcing
ampsal(:,:,:), & !< The amplitude of the SAL [Z ~> m].
cosphase_prev(:,:,:), & !< The cosine of the phase of the amphidromes in the previous tidal solutions [nondim].
sinphase_prev(:,:,:), & !< The sine of the phase of the amphidromes in the previous tidal solutions [nondim].
amp_prev(:,:,:) !< The amplitude of the previous tidal solution [Z ~> m].
amp_prev(:,:,:), & !< The amplitude of the previous tidal solution [Z ~> m].
tide_fn(:), & !< Amplitude modulation of tides by nodal cycle [nondim].
tide_un(:) !< Phase modulation of tides by nodal cycle [rad].
end type tidal_forcing_CS

integer :: id_clock_tides !< CPU clock for tides
Expand Down Expand Up @@ -251,9 +253,14 @@ subroutine tidal_forcing_init(Time, G, US, param_file, CS, HA_CS)
real, dimension(MAX_CONSTITUENTS) :: amp_def ! Default amplitude for each tidal constituent [m]
real, dimension(MAX_CONSTITUENTS) :: love_def ! Default love number for each constituent [nondim]
integer, dimension(3) :: tide_ref_date !< Reference date (t = 0) for tidal forcing.
integer, dimension(3) :: nodal_ref_date !< Reference date for calculating nodal modulation for tidal forcing.
logical :: use_M2, use_S2, use_N2, use_K2, use_K1, use_O1, use_P1, use_Q1
logical :: use_MF, use_MM
logical :: tides ! True if a tidal forcing is to be used.
logical :: add_nodal_terms = .false. !< If true, insert terms for the 18.6 year modulation when
!! calculating tidal forcing.
type(time_type) :: nodal_time !< Model time to calculate nodal modulation for.
type(astro_longitudes) :: nodal_longitudes !< Solar and lunar longitudes for tidal forcing
logical :: HA_ssh, HA_ubt, HA_vbt
! This include declares and sets the variable "version".
# include "version_variable.h"
Expand Down Expand Up @@ -528,8 +535,46 @@ subroutine tidal_forcing_init(Time, G, US, param_file, CS, HA_CS)
enddo
endif

call get_param(param_file, mdl, "TIDE_ADD_NODAL", add_nodal_terms, &
"If true, include 18.6 year nodal modulation in the astronomical tidal forcing.", &
default=.false.)
call get_param(param_file, mdl, "TIDE_NODAL_REF_DATE", nodal_ref_date, &
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"Fixed reference date to use for nodal modulation of astronomical tidal forcing.", &
fail_if_missing=.false., default=0)

! If the nodal correction is based on a different time, initialize that.
! Otherwise, it can use N from the time reference.
if (add_nodal_terms) then
if (sum(nodal_ref_date) /= 0) then
! A reference date was provided for the nodal correction
nodal_time = set_date(nodal_ref_date(1), nodal_ref_date(2), nodal_ref_date(3))
call astro_longitudes_init(nodal_time, nodal_longitudes)
elseif (CS%use_eq_phase) then
! Astronomical longitudes were already calculated for use in equilibrium phases,
! so use nodal longitude from that.
nodal_longitudes = CS%tidal_longitudes
else
! Tidal reference time is a required parameter, so calculate the longitudes from that.
call astro_longitudes_init(CS%time_ref, nodal_longitudes)
endif
endif

allocate(CS%tide_fn(nc))
allocate(CS%tide_un(nc))

do c=1,nc
! Find nodal corrections if needed
if (add_nodal_terms) then
call nodal_fu(trim(CS%const_name(c)), nodal_longitudes%N, CS%tide_fn(c), CS%tide_un(c))
else
CS%tide_fn(c) = 1.0
CS%tide_un(c) = 0.0
endif
enddo

if (present(HA_CS)) then
call HA_init(Time, US, param_file, CS%time_ref, CS%nc, CS%freq, CS%phase0, CS%const_name, HA_CS)
call HA_init(Time, US, param_file, CS%time_ref, CS%nc, CS%freq, CS%phase0, CS%const_name, &
CS%tide_fn, CS%tide_un, HA_CS)
call get_param(param_file, mdl, "HA_SSH", HA_ssh, &
"If true, perform harmonic analysis of sea serface height.", default=.false.)
if (HA_ssh) call HA_register('ssh', 'h', HA_CS)
Expand Down Expand Up @@ -614,26 +659,26 @@ subroutine calc_tidal_forcing(Time, e_tide_eq, e_tide_sal, G, US, CS)

do c=1,CS%nc
m = CS%struct(c)
amp_cosomegat = CS%amp(c)*CS%love_no(c) * cos(CS%freq(c)*now + CS%phase0(c))
amp_sinomegat = CS%amp(c)*CS%love_no(c) * sin(CS%freq(c)*now + CS%phase0(c))
amp_cosomegat = CS%amp(c)*CS%love_no(c)*CS%tide_fn(c) * cos(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
amp_sinomegat = CS%amp(c)*CS%love_no(c)*CS%tide_fn(c) * sin(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
do j=Jsq,Jeq+1 ; do i=Isq,Ieq+1
e_tide_eq(i,j) = e_tide_eq(i,j) + (amp_cosomegat*CS%cos_struct(i,j,m) + &
amp_sinomegat*CS%sin_struct(i,j,m))
enddo ; enddo
enddo

if (CS%use_tidal_sal_file) then ; do c=1,CS%nc
cosomegat = cos(CS%freq(c)*now)
sinomegat = sin(CS%freq(c)*now)
cosomegat = CS%tide_fn(c) * cos(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
sinomegat = CS%tide_fn(c) * sin(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
do j=Jsq,Jeq+1 ; do i=Isq,Ieq+1
e_tide_sal(i,j) = e_tide_sal(i,j) + CS%ampsal(i,j,c) * &
(cosomegat*CS%cosphasesal(i,j,c) + sinomegat*CS%sinphasesal(i,j,c))
enddo ; enddo
enddo ; endif

if (CS%use_tidal_sal_prev) then ; do c=1,CS%nc
cosomegat = cos(CS%freq(c)*now)
sinomegat = sin(CS%freq(c)*now)
cosomegat = CS%tide_fn(c) * cos(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
sinomegat = CS%tide_fn(c) * sin(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
do j=Jsq,Jeq+1 ; do i=Isq,Ieq+1
e_tide_sal(i,j) = e_tide_sal(i,j) - CS%sal_scalar * CS%amp_prev(i,j,c) * &
(cosomegat*CS%cosphase_prev(i,j,c) + sinomegat*CS%sinphase_prev(i,j,c))
Expand Down Expand Up @@ -692,8 +737,8 @@ subroutine calc_tidal_forcing_legacy(Time, e_sal, e_sal_tide, e_tide_eq, e_tide_

do c=1,CS%nc
m = CS%struct(c)
amp_cosomegat = CS%amp(c)*CS%love_no(c) * cos(CS%freq(c)*now + CS%phase0(c))
amp_sinomegat = CS%amp(c)*CS%love_no(c) * sin(CS%freq(c)*now + CS%phase0(c))
amp_cosomegat = CS%amp(c)*CS%love_no(c)*CS%tide_fn(c) * cos(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
amp_sinomegat = CS%amp(c)*CS%love_no(c)*CS%tide_fn(c) * sin(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
do j=Jsq,Jeq+1 ; do i=Isq,Ieq+1
amp_cossin = (amp_cosomegat*CS%cos_struct(i,j,m) + amp_sinomegat*CS%sin_struct(i,j,m))
e_sal_tide(i,j) = e_sal_tide(i,j) + amp_cossin
Expand All @@ -702,8 +747,8 @@ subroutine calc_tidal_forcing_legacy(Time, e_sal, e_sal_tide, e_tide_eq, e_tide_
enddo

if (CS%use_tidal_sal_file) then ; do c=1,CS%nc
cosomegat = cos(CS%freq(c)*now)
sinomegat = sin(CS%freq(c)*now)
cosomegat = CS%tide_fn(c) * cos(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
sinomegat = CS%tide_fn(c) * sin(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
do j=Jsq,Jeq+1 ; do i=Isq,Ieq+1
amp_cossin = CS%ampsal(i,j,c) &
* (cosomegat*CS%cosphasesal(i,j,c) + sinomegat*CS%sinphasesal(i,j,c))
Expand All @@ -713,8 +758,8 @@ subroutine calc_tidal_forcing_legacy(Time, e_sal, e_sal_tide, e_tide_eq, e_tide_
enddo ; endif

if (CS%use_tidal_sal_prev) then ; do c=1,CS%nc
cosomegat = cos(CS%freq(c)*now)
sinomegat = sin(CS%freq(c)*now)
cosomegat = CS%tide_fn(c) * cos(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
sinomegat = CS%tide_fn(c) * sin(CS%freq(c)*now + CS%phase0(c) + CS%tide_un(c))
do j=Jsq,Jeq+1 ; do i=Isq,Ieq+1
amp_cossin = -CS%sal_scalar * CS%amp_prev(i,j,c) &
* (cosomegat*CS%cosphase_prev(i,j,c) + sinomegat*CS%sinphase_prev(i,j,c))
Expand Down
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