+Added 9 ..._ANSWER_DATE runtime parameters

Added 9 ..._ANSWER_DATE runtime parameters controlling the expressions and order of arithmetic in the parameterizations modules, which take precedence over their older ..._ANSWERS_2018 counterparts. The new runtime parameters are HOR_VISC_ANSWER_DATE, MEKE_GEOMETRIC_ANSWER_DATE, EPBL_ANSWER_DATE, OPTICS_ANSWER_DATE, REGULARIZE_LAYERS_ANSWER_DATE, SET_DIFF_ANSWER_DATE, SET_VISC_ANSWER_DATE, TIDAL_MIXING_ANSWER_DATE and VERT_FRICTION_ANSWER_DATE. All answers are bitwise identical, but there are numerous new entries in the MOM_parameter_doc.all files.
NOAA-GFDL · Jul 31, 2022 · a32b840 · a32b840
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diff --git a/src/parameterizations/lateral/MOM_hor_visc.F90 b/src/parameterizations/lateral/MOM_hor_visc.F90
@@ -92,9 +92,10 @@ module MOM_hor_visc
   logical :: res_scale_MEKE  !< If true, the viscosity contribution from MEKE is scaled by
                              !! the resolution function.
   logical :: use_GME         !< If true, use GME backscatter scheme.
-  logical :: answers_2018    !< If true, use the order of arithmetic and expressions that recover the
-                             !! answers from the end of 2018.  Otherwise, use updated and more robust
-                             !! forms of the same expressions.
+  integer :: answer_date     !< The vintage of the order of arithmetic and expressions in the
+                             !! horizontal viscosity calculations.  Values below 20190101 recover
+                             !! the answers from the end of 2018, while higher values use updated
+                             !! and more robust forms of the same expressions.
   real    :: GME_h0          !< The strength of GME tapers quadratically to zero when the bathymetric
                              !! depth is shallower than GME_H0 [Z ~> m]
   real    :: GME_efficiency  !< The nondimensional prefactor multiplying the GME coefficient [nondim]
@@ -1549,7 +1550,7 @@ subroutine horizontal_viscosity(u, v, h, diffu, diffv, MEKE, VarMix, G, GV, US,
           Shear_mag_bc = sqrt(sh_xx(i,j) * sh_xx(i,j) + &
             0.25*((sh_xy(I-1,J-1)*sh_xy(I-1,J-1) + sh_xy(I,J)*sh_xy(I,J)) + &
                   (sh_xy(I-1,J)*sh_xy(I-1,J) + sh_xy(I,J-1)*sh_xy(I,J-1))))
-          if (CS%answers_2018) then
+          if (CS%answer_date > 20190101) then
             FatH = (US%s_to_T*FatH)**MEKE%backscatter_Ro_pow ! f^n
             ! Note the hard-coded dimensional constant in the following line that can not
             ! be rescaled for dimensional consistency.
@@ -1724,7 +1725,11 @@ subroutine hor_visc_init(Time, G, GV, US, param_file, diag, CS, ADp)
   logical :: split         ! If true, use the split time stepping scheme.
                            ! If false and USE_GME = True, issue a FATAL error.
   logical :: use_MEKE      ! If true, the MEKE parameterization is in use.
-  logical :: default_2018_answers
+  logical :: answers_2018  ! If true, use the order of arithmetic and expressions that recover the
+                           ! answers from the end of 2018.  Otherwise, use updated and more robust
+                           ! forms of the same expressions.
+  integer :: default_answer_date  ! The default setting for the various ANSWER_DATE flags
+  logical :: default_2018_answers ! The default setting for the various 2018_ANSWERS flags
   character(len=64) :: inputdir, filename
   real    :: deg2rad       ! Converts degrees to radians
   real    :: slat_fn       ! sin(lat)**Kh_pwr_of_sine
@@ -1748,13 +1753,26 @@ subroutine hor_visc_init(Time, G, GV, US, param_file, diag, CS, ADp)
   call log_version(param_file, mdl, version, "")
 
   ! All parameters are read in all cases to enable parameter spelling checks.
+  call get_param(param_file, mdl, "DEFAULT_ANSWER_DATE", default_answer_date, &
+                 "This sets the default value for the various _ANSWER_DATE parameters.", &
+                 default=99991231)
   call get_param(param_file, mdl, "DEFAULT_2018_ANSWERS", default_2018_answers, &
                  "This sets the default value for the various _2018_ANSWERS parameters.", &
-                 default=.false.)
-  call get_param(param_file, mdl, "HOR_VISC_2018_ANSWERS", CS%answers_2018, &
+                 default=(default_answer_date<20190101))
+  call get_param(param_file, mdl, "HOR_VISC_2018_ANSWERS", answers_2018, &
                  "If true, use the order of arithmetic and expressions that recover the "//&
                  "answers from the end of 2018.  Otherwise, use updated and more robust "//&
                  "forms of the same expressions.", default=default_2018_answers)
+  ! Revise inconsistent default answer dates for horizontal viscosity.
+  if (answers_2018 .and. (default_answer_date >= 20190101)) default_answer_date = 20181231
+  if (.not.answers_2018 .and. (default_answer_date < 20190101)) default_answer_date = 20190101
+  call get_param(param_file, mdl, "HOR_VISC_ANSWER_DATE", CS%answer_date, &
+                 "The vintage of the order of arithmetic and expressions in the horizontal "//&
+                 "viscosity calculations.  Values below 20190101 recover the answers from the "//&
+                 "end of 2018, while higher values use updated and more robust forms of the "//&
+                 "same expressions.  If both HOR_VISC_2018_ANSWERS and HOR_VISC_ANSWER_DATE are "//&
+                 "specified, the latter takes precedence.", default=default_answer_date)
+
   call get_param(param_file, mdl, "DEBUG", CS%debug, default=.false.)
   call get_param(param_file, mdl, "LAPLACIAN", CS%Laplacian, &
                  "If true, use a Laplacian horizontal viscosity.", &

diff --git a/src/parameterizations/lateral/MOM_thickness_diffuse.F90 b/src/parameterizations/lateral/MOM_thickness_diffuse.F90
@@ -72,9 +72,10 @@ module MOM_thickness_diffuse
                                  !! the GEOMETRIC thickness diffusion [nondim]
   real    :: MEKE_GEOMETRIC_epsilon !< Minimum Eady growth rate for the GEOMETRIC thickness
                                  !! diffusivity [T-1 ~> s-1].
-  logical :: MEKE_GEOM_answers_2018  !< If true, use expressions in the MEKE_GEOMETRIC calculation
-                                 !! that recover the answers from the original implementation.
-                                 !! Otherwise, use expressions that satisfy rotational symmetry.
+  integer :: MEKE_GEOM_answer_date  !< The vintage of the expressions in the MEKE_GEOMETRIC
+                                 !! calculation.  Values below 20190101 recover the answers from the
+                                 !! original implementation, while higher values use expressions that
+                                 !! satisfy rotational symmetry.
   logical :: Use_KH_in_MEKE      !< If true, uses the thickness diffusivity calculated here to diffuse MEKE.
   logical :: GM_src_alt          !< If true, use the GM energy conversion form S^2*N^2*kappa rather
                                  !! than the streamfunction for the GM source term.
@@ -392,7 +393,7 @@ subroutine thickness_diffuse(h, uhtr, vhtr, tv, dt, G, GV, US, MEKE, VarMix, CDp
 
   if (allocated(MEKE%Kh)) then
     if (CS%MEKE_GEOMETRIC) then
-      if (CS%MEKE_GEOM_answers_2018) then
+      if (CS%MEKE_GEOM_answer_date < 20190101) then
         !$OMP do
         do j=js,je ; do I=is,ie
           ! This does not give bitwise rotational symmetry.
@@ -1950,7 +1951,11 @@ subroutine thickness_diffuse_init(Time, G, GV, US, param_file, diag, CDp, CS)
   real :: strat_floor  ! A floor for buoyancy frequency in the Ferrari et al. 2010,
                        ! streamfunction formulation, expressed as a fraction of planetary
                        ! rotation [nondim].
+  integer :: default_answer_date  ! The default setting for the various ANSWER_DATE flags.
   logical :: default_2018_answers ! The default setting for the various 2018_ANSWERS flags.
+  logical :: MEKE_GEOM_answers_2018  ! If true, use expressions in the MEKE_GEOMETRIC calculation
+                                  ! that recover the answers from the original implementation.
+                                  ! Otherwise, use expressions that satisfy rotational symmetry.
   integer :: i, j
 
   CS%initialized = .true.
@@ -2068,13 +2073,25 @@ subroutine thickness_diffuse_init(Time, G, GV, US, param_file, diag, CDp, CS)
                  "The nondimensional coefficient governing the efficiency of the GEOMETRIC "//&
                  "thickness diffusion.", units="nondim", default=0.05)
 
+    call get_param(param_file, mdl, "DEFAULT_ANSWER_DATE", default_answer_date, &
+                 "This sets the default value for the various _ANSWER_DATE parameters.", &
+                 default=99991231)
     call get_param(param_file, mdl, "DEFAULT_2018_ANSWERS", default_2018_answers, &
                  "This sets the default value for the various _2018_ANSWERS parameters.", &
-                 default=.false.)
-    call get_param(param_file, mdl, "MEKE_GEOMETRIC_2018_ANSWERS", CS%MEKE_GEOM_answers_2018, &
+                 default=(default_answer_date<20190101))
+    call get_param(param_file, mdl, "MEKE_GEOMETRIC_2018_ANSWERS", MEKE_GEOM_answers_2018, &
                  "If true, use expressions in the MEKE_GEOMETRIC calculation that recover the "//&
                  "answers from the original implementation.  Otherwise, use expressions that "//&
                  "satisfy rotational symmetry.", default=default_2018_answers)
+    ! Revise inconsistent default answer dates for MEKE_geometric.
+    if (MEKE_GEOM_answers_2018 .and. (default_answer_date >= 20190101)) default_answer_date = 20181231
+    if (.not.MEKE_GEOM_answers_2018 .and. (default_answer_date < 20190101)) default_answer_date = 20190101
+    call get_param(param_file, mdl, "MEKE_GEOMETRIC_ANSWER_DATE", CS%MEKE_GEOM_answer_date, &
+                 "The vintage of the expressions in the MEKE_GEOMETRIC calculation.  "//&
+                 "Values below 20190101 recover the answers from the original implementation, "//&
+                 "while higher values use expressions that satisfy rotational symmetry.  "//&
+                 "If both MEKE_GEOMETRIC_2018_ANSWERS and MEKE_GEOMETRIC_ANSWER_DATE are "//&
+                 "specified, the latter takes precedence.", default=default_answer_date)
   endif
 
   call get_param(param_file, mdl, "USE_KH_IN_MEKE", CS%Use_KH_in_MEKE, &

diff --git a/src/parameterizations/vertical/MOM_energetic_PBL.F90 b/src/parameterizations/vertical/MOM_energetic_PBL.F90
@@ -158,9 +158,10 @@ module MOM_energetic_PBL
   type(time_type), pointer :: Time=>NULL() !< A pointer to the ocean model's clock.
 
   logical :: TKE_diagnostics = .false. !< If true, diagnostics of the TKE budget are being calculated.
-  logical :: answers_2018    !< If true, use the order of arithmetic and expressions that recover the
-                             !! answers from the end of 2018.  Otherwise, use updated and more robust
-                             !! forms of the same expressions.
+  integer :: answer_date     !< The vintage of the order of arithmetic and expressions in the ePBL
+                             !! calculations.  Values below 20190101 recover the answers from the
+                             !! end of 2018, while higher values use updated and more robust forms
+                             !! of the same expressions.
   logical :: orig_PE_calc    !< If true, the ePBL code uses the original form of the
                              !! potential energy change code.  Otherwise, it uses a newer version
                              !! that can work with successive increments to the diffusivity in
@@ -828,7 +829,7 @@ subroutine ePBL_column(h, u, v, T0, S0, dSV_dT, dSV_dS, TKE_forcing, B_flux, abs
       endif
 
       !/ Apply MStar to get mech_TKE
-      if ((CS%answers_2018) .and. (CS%mstar_scheme==Use_Fixed_MStar)) then
+      if ((CS%answer_date < 20190101) .and. (CS%mstar_scheme==Use_Fixed_MStar)) then
         mech_TKE = (dt*MSTAR_total*GV%Rho0) * u_star**3
       else
         mech_TKE = MSTAR_total * (dt*GV%Rho0* u_star**3)
@@ -1760,7 +1761,7 @@ subroutine find_mstar(CS, US, Buoyancy_Flux, UStar, UStar_Mean,&
   !/ 1. Get mstar
   elseif (CS%mstar_scheme == MStar_from_Ekman) then
 
-    if (CS%answers_2018) then
+    if (CS%answer_date < 20190101) then
       ! The limit for the balance of rotation and stabilizing is f(L_Ekman,L_Obukhov)
       MStar_S = CS%MStar_coef*sqrt(max(0.0,Buoyancy_Flux) / UStar**2 / &
                     (Abs_Coriolis + 1.e-10*US%T_to_s) )
@@ -1778,7 +1779,7 @@ subroutine find_mstar(CS, US, Buoyancy_Flux, UStar, UStar_Mean,&
     MStar = max(MStar_S, min(1.25, MStar_N))
     if (CS%MStar_Cap > 0.0) MStar = min( CS%MStar_Cap,MStar )
   elseif ( CS%mstar_scheme == MStar_from_RH18 ) then
-    if (CS%answers_2018) then
+    if (CS%answer_date < 20190101) then
       MStar_N = CS%RH18_MStar_cn1 * ( 1.0 - 1.0 / ( 1. + CS%RH18_MStar_cn2 * &
                 exp( CS%RH18_mstar_CN3 * BLD * Abs_Coriolis / UStar) ) )
     else
@@ -1791,7 +1792,7 @@ subroutine find_mstar(CS, US, Buoyancy_Flux, UStar, UStar_Mean,&
   endif
 
   !/ 2. Adjust mstar to account for convective turbulence
-  if (CS%answers_2018) then
+  if (CS%answer_date < 20190101) then
     MStar_Conv_Red = 1. - CS%MStar_Convect_coef * (-min(0.0,Buoyancy_Flux) + 1.e-10*US%T_to_s**3*US%m_to_Z**2) / &
                          ( (-min(0.0,Buoyancy_Flux) + 1.e-10*US%T_to_s**3*US%m_to_Z**2) + &
                          2.0 *MStar * UStar**3 / BLD )
@@ -1851,7 +1852,7 @@ subroutine Mstar_Langmuir(CS, US, Abs_Coriolis, Buoyancy_Flux, UStar, BLD, Langm
 
   if (CS%LT_Enhance_Form /= No_Langmuir) then
     ! a. Get parameters for modified LA
-    if (CS%answers_2018) then
+    if (CS%answer_date < 20190101) then
       iL_Ekman   = Abs_Coriolis / Ustar
       iL_Obukhov = Buoyancy_Flux*CS%vonkar / Ustar**3
       Ekman_Obukhov_stab = abs(max(0., iL_Obukhov / (iL_Ekman + 1.e-10*US%Z_to_m)))
@@ -1942,7 +1943,11 @@ subroutine energetic_PBL_init(Time, G, GV, US, param_file, diag, CS)
   real :: omega_frac_dflt
   integer :: isd, ied, jsd, jed
   integer :: mstar_mode, LT_enhance, wT_mode
-  logical :: default_2018_answers
+  integer :: default_answer_date  ! The default setting for the various ANSWER_DATE flags.
+  logical :: default_2018_answers ! The default setting for the various 2018_ANSWERS flags.
+  logical :: answers_2018  ! If true, use the order of arithmetic and expressions that recover the
+                           ! answers from the end of 2018.  Otherwise, use updated and more robust
+                           ! forms of the same expressions.
   logical :: use_temperature, use_omega
   logical :: use_la_windsea
   isd = G%isd ; ied = G%ied ; jsd = G%jsd ; jed = G%jed
@@ -1977,13 +1982,25 @@ subroutine energetic_PBL_init(Time, G, GV, US, param_file, diag, CS)
                  "A nondimensional scaling factor controlling the inhibition "//&
                  "of the diffusive length scale by rotation. Making this larger "//&
                  "decreases the PBL diffusivity.", units="nondim", default=1.0)
+  call get_param(param_file, mdl, "DEFAULT_ANSWER_DATE", default_answer_date, &
+                 "This sets the default value for the various _ANSWER_DATE parameters.", &
+                 default=99991231)
   call get_param(param_file, mdl, "DEFAULT_2018_ANSWERS", default_2018_answers, &
                  "This sets the default value for the various _2018_ANSWERS parameters.", &
-                 default=.false.)
-  call get_param(param_file, mdl, "EPBL_2018_ANSWERS", CS%answers_2018, &
+                 default=(default_answer_date<20190101))
+  call get_param(param_file, mdl, "EPBL_2018_ANSWERS", answers_2018, &
                  "If true, use the order of arithmetic and expressions that recover the "//&
                  "answers from the end of 2018.  Otherwise, use updated and more robust "//&
                  "forms of the same expressions.", default=default_2018_answers)
+  ! Revise inconsistent default answer dates for horizontal viscosity.
+  if (answers_2018 .and. (default_answer_date >= 20190101)) default_answer_date = 20181231
+  if (.not.answers_2018 .and. (default_answer_date < 20190101)) default_answer_date = 20190101
+  call get_param(param_file, mdl, "EPBL_ANSWER_DATE", CS%answer_date, &
+                 "The vintage of the order of arithmetic and expressions in the energetic "//&
+                 "PBL calculations.  Values below 20190101 recover the answers from the "//&
+                 "end of 2018, while higher values use updated and more robust forms of the "//&
+                 "same expressions.  If both EPBL_2018_ANSWERS and EPBL_ANSWER_DATE are "//&
+                 "specified, the latter takes precedence.", default=default_answer_date)
 
 
   call get_param(param_file, mdl, "EPBL_ORIGINAL_PE_CALC", CS%orig_PE_calc, &