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Document variables in diagnoseMLDbyEnergy
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  Added comments documenting the units of the variables in diagnoseMLDbyEnergy
and slightly refactored this routine to clean up its call to calculate_density
and eliminated a redundant array of interface depths.  Also fixed several
spelling errors in comments. All answers and diagnostics are bitwise identical.
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@Hallberg-NOAA
Hallberg-NOAA committed Apr 26, 2022
1 parent 548be25 commit 9c2e573
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Showing 2 changed files with 53 additions and 31 deletions.
82 changes: 52 additions & 30 deletions src/parameterizations/vertical/MOM_diabatic_aux.F90
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Original file line number Diff line number Diff line change
Expand Up @@ -220,7 +220,7 @@ subroutine make_frazil(h, tv, G, GV, US, CS, p_surf, halo)

end subroutine make_frazil

!> This subroutine applies double diffusion to T & S, assuming no diapycal mass
!> This subroutine applies double diffusion to T & S, assuming no diapycnal mass
!! fluxes, using a simple triadiagonal solver.
subroutine differential_diffuse_T_S(h, T, S, Kd_T, Kd_S, dt, G, GV)
type(ocean_grid_type), intent(in) :: G !< The ocean's grid structure
Expand Down Expand Up @@ -604,8 +604,8 @@ subroutine set_pen_shortwave(optics, fluxes, G, GV, US, CS, opacity, tracer_flow
!! organizing the tracer modules.

! Local variables
real, dimension(SZI_(G),SZJ_(G)) :: chl_2d !< Vertically uniform chlorophyll-A concentractions [mg m-3]
real, dimension(SZI_(G),SZJ_(G),SZK_(GV)) :: chl_3d !< The chlorophyll-A concentractions of each layer [mg m-3]
real, dimension(SZI_(G),SZJ_(G)) :: chl_2d !< Vertically uniform chlorophyll-A concentrations [mg m-3]
real, dimension(SZI_(G),SZJ_(G),SZK_(GV)) :: chl_3d !< The chlorophyll-A concentrations of each layer [mg m-3]
character(len=128) :: mesg
integer :: i, j, is, ie, js, je
is = G%isc ; ie = G%iec ; js = G%jsc ; je = G%jec
Expand Down Expand Up @@ -676,7 +676,7 @@ subroutine diagnoseMLDbyDensityDifference(id_MLD, h, tv, densityDiff, G, GV, US,
real, dimension(SZI_(G)) :: S_subML, S_deeper ! Salinities used in the N2 calculation [ppt].
real, dimension(SZI_(G)) :: rho_subML, rho_deeper ! Densities used in the N2 calculation [R ~> kg m-3].
real, dimension(SZI_(G)) :: dK, dKm1 ! Depths [Z ~> m].
real, dimension(SZI_(G)) :: rhoSurf ! Density used in finding the mixedlayer depth [R ~> kg m-3].
real, dimension(SZI_(G)) :: rhoSurf ! Density used in finding the mixed layer depth [R ~> kg m-3].
real, dimension(SZI_(G), SZJ_(G)) :: MLD ! Diagnosed mixed layer depth [Z ~> m].
real, dimension(SZI_(G), SZJ_(G)) :: subMLN2 ! Diagnosed stratification below ML [T-2 ~> s-2].
real, dimension(SZI_(G), SZJ_(G)) :: MLD2 ! Diagnosed MLD^2 [Z2 ~> m2].
Expand Down Expand Up @@ -801,32 +801,59 @@ subroutine diagnoseMLDbyEnergy(id_MLD, h, tv, G, GV, US, Mixing_Energy, diagPtr)
! density in the mixed layer as well as in the remaining part of the present layer that is
! not mixed.
! To solve for X in this equation a Newton's method iteration is employed, which
! converges extremely quickly (usually 1 guess) since this equation turns out being rather
! lienar for PE change with increasing X.
! converges extremely quickly (usually 1 guess) since this equation turns out to be rather
! linear for PE change with increasing X.
! Input parameters:
integer, dimension(3), intent(in) :: id_MLD !< Energy output diag IDs
type(ocean_grid_type), intent(in) :: G !< Grid type
type(verticalGrid_type), intent(in) :: GV !< ocean vertical grid structure
type(unit_scale_type), intent(in) :: US !< A dimensional unit scaling type
real, dimension(3), intent(in) :: Mixing_Energy !< Energy values for up to 3 MLDs
real, dimension(3), intent(in) :: Mixing_Energy !< Energy values for up to 3 MLDs [R Z L2 T-2 ~> J m-2]
real, dimension(SZI_(G),SZJ_(G),SZK_(GV)), &
intent(in) :: h !< Layer thickness [H ~> m or kg m-2]
type(thermo_var_ptrs), intent(in) :: tv !< Structure containing pointers to any
!! available thermodynamic fields.
type(diag_ctrl), pointer :: diagPtr !< Diagnostics structure

! Local variables
real, dimension(SZI_(G), SZJ_(G),3) :: MLD ! Diagnosed mixed layer depth [Z ~> m].
real, dimension(SZK_(GV)) :: Z_L, Z_U, dZ, Rho_c, pRef_MLD
real, dimension(3) :: PE_threshold

real :: PE_Threshold_fraction, PE, PE_Mixed, PE_Mixed_TST
real :: RhoDZ_ML, H_ML, RhoDZ_ML_TST, H_ML_TST
real :: Rho_ML

real :: R1, D1, R2, D2
real :: Ca, Cb,D ,Cc, Cd, Ca2, Cb2, C, Cc2
real :: Gx, Gpx, Hx, iHx, Hpx, Ix, Ipx, Fgx, Fpx, X, X2
real, dimension(SZI_(G),SZJ_(G),3) :: MLD ! Diagnosed mixed layer depth [Z ~> m].
real, dimension(SZK_(GV)+1) :: Z_int ! Depths of the interfaces from the surface [Z ~> m]
real, dimension(SZK_(GV)) :: dZ ! Layer thicknesses in depth units [Z ~> m]
real, dimension(SZK_(GV)) :: Rho_c ! A column of layer densities [R ~> kg m-3]
real, dimension(SZK_(GV)) :: pRef_MLD ! The reference pressure for the mixed layer
! depth calculation [R L2 T-2 ~> Pa]
real, dimension(3) :: PE_threshold ! The energy threshold divided by g [R Z2 ~> kg m-1]

real :: PE_Threshold_fraction ! The fractional tolerance of the specified energy
! for the energy used to mix to the diagnosed depth [nondim]
real :: H_ML ! The accumulated depth of the mixed layer [Z ~> m]
real :: PE ! The cumulative potential energy of the unmixed water column to a depth
! of H_ML, divided by the gravitational acceleration [R Z2 ~> kg m-1]
real :: PE_Mixed ! The potential energy of the completely mixed water column to a depth
! of H_ML, divided by the gravitational acceleration [R Z2 ~> kg m-1]
real :: RhoDZ_ML ! The depth integrated density of the mixed layer [R Z ~> kg m-2]
real :: H_ML_TST ! A new test value for the depth of the mixed layer [Z ~> m]
real :: PE_Mixed_TST ! The potential energy of the completely mixed water column to a depth
! of H_ML_TST, divided by the gravitational acceleration [R Z2 ~> kg m-1]
real :: RhoDZ_ML_TST ! A test value of the new depth integrated density of the mixed layer [R Z ~> kg m-2]
real :: Rho_ML ! The average density of the mixed layer [R ~> kg m-3]

! These are all temporary variables used to shorten the expressions in the iterations.
real :: R1, R2, Ca, Ca2 ! Some densities [R ~> kg m-3]
real :: D1, D2, X, X2 ! Some thicknesses [Z ~> m]
real :: Cb, Cb2 ! A depth integrated density [R Z ~> kg m-2]
real :: C, D ! A depth squared [Z2 ~> m2]
real :: Cc, Cc2 ! A density times a depth squared [R Z2 ~> kg m-1]
real :: Cd ! A density times a depth cubed [R Z3 ~> kg]
real :: Gx ! A triple integral in depth of density [R Z3 ~> kg]
real :: Gpx ! The derivative of Gx with x [R Z2 ~> kg m-1]
real :: Hx ! The vertical integral depth [Z ~> m]
real :: iHx ! The inverse of Hx [Z-1 ~> m-1]
real :: Hpx ! The derivative of Hx with x, hard coded to 1. Why? [nondim]
real :: Ix ! A double integral in depth of density [R Z2 ~> kg m-1]
real :: Ipx ! The derivative of Ix with x [R Z ~> kg m-2]
real :: Fgx ! The mixing energy difference from the target [R Z2 ~> kg m-1]
real :: Fpx ! The derivative of Fgx with x [R Z ~> kg m-2]

integer :: IT, iM
integer :: i, j, is, ie, js, je, k, nz
Expand All @@ -844,17 +871,12 @@ subroutine diagnoseMLDbyEnergy(id_MLD, h, tv, G, GV, US, Mixing_Energy, diagPtr)
do j=js,je ; do i=is,ie
if (G%mask2dT(i,j) > 0.0) then

call calculate_density(tv%T(i,j,:), tv%S(i,j,:), pRef_MLD, rho_c, 1, nz, &
tv%eqn_of_state, scale=US%kg_m3_to_R)
call calculate_density(tv%T(i,j,:), tv%S(i,j,:), pRef_MLD, rho_c, tv%eqn_of_state)

Z_int(1) = 0.0
do k=1,nz
DZ(k) = h(i,j,k) * GV%H_to_Z
enddo
Z_U(1) = 0.0
Z_L(1) = -DZ(1)
do k=2,nz
Z_U(k) = Z_L(k-1)
Z_L(k) = Z_L(k-1)-DZ(k)
Z_int(K+1) = Z_int(K) - DZ(k)
enddo

do iM=1,3
Expand All @@ -870,7 +892,7 @@ subroutine diagnoseMLDbyEnergy(id_MLD, h, tv, G, GV, US, Mixing_Energy, diagPtr)
do k=1,nz

! This is the unmixed PE cumulative sum from top down
PE = PE + 0.5 * rho_c(k) * (Z_U(k)**2 - Z_L(k)**2)
PE = PE + 0.5 * rho_c(k) * (Z_int(K)**2 - Z_int(K+1)**2)

! This is the depth and integral of density
H_ML_TST = H_ML + DZ(k)
Expand Down Expand Up @@ -1067,7 +1089,7 @@ subroutine applyBoundaryFluxesInOut(CS, G, GV, US, dt, fluxes, optics, nsw, h, t
! [degC H T-1 ~> degC m s-1 or degC kg m-2 s-1]
real, dimension(max(nsw,1),SZI_(G),SZK_(GV)) :: &
opacityBand ! The opacity (inverse of the exponential absorption length) of each frequency
! band of shortwave radation in each layer [H-1 ~> m-1 or m2 kg-1]
! band of shortwave radiation in each layer [H-1 ~> m-1 or m2 kg-1]
real, dimension(maxGroundings) :: hGrounding ! Thickness added by each grounding event [H ~> m or kg m-2]
real :: Temp_in, Salin_in
real :: g_Hconv2 ! A conversion factor for use in the TKE calculation
Expand Down Expand Up @@ -1173,7 +1195,7 @@ subroutine applyBoundaryFluxesInOut(CS, G, GV, US, dt, fluxes, optics, nsw, h, t
! netSalt = surface salt fluxes [ppt H ~> ppt m or gSalt m-2]
! Pen_SW_bnd = components to penetrative shortwave radiation split according to bands.
! This field provides that portion of SW from atmosphere that in fact
! enters to the ocean and participates in pentrative SW heating.
! enters to the ocean and participates in penetrative SW heating.
! nonpenSW = non-downwelling SW flux, which is absorbed in ocean surface
! (in tandem w/ LW,SENS,LAT); saved only for diagnostic purposes.

Expand Down Expand Up @@ -1201,7 +1223,7 @@ subroutine applyBoundaryFluxesInOut(CS, G, GV, US, dt, fluxes, optics, nsw, h, t
! For all these reasons we compute additional values of <_rate> which are preserved
! for the buoyancy flux calculation and reproduce the old answers.
! In the future this needs more detailed investigation to make sure everything is
! consistent and correct. These details shouldnt significantly effect climate,
! consistent and correct. These details should not significantly effect climate,
! but do change answers.
!-----------------------------------------------------------------------------------------
if (calculate_buoyancy) then
Expand Down
2 changes: 1 addition & 1 deletion src/parameterizations/vertical/MOM_diabatic_driver.F90
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Original file line number Diff line number Diff line change
Expand Up @@ -171,7 +171,7 @@ module MOM_diabatic_driver
real :: MLDdensityDifference !< Density difference used to determine MLD_user [R ~> kg m-3]
real :: dz_subML_N2 !< The distance over which to calculate a diagnostic of the
!! average stratification at the base of the mixed layer [Z ~> m].
real :: MLD_EN_VALS(3) !< Energy values for energy mixed layer diagnostics
real :: MLD_EN_VALS(3) !< Energy values for energy mixed layer diagnostics [R Z L2 T-2 ~> J m-2]

!>@{ Diagnostic IDs
integer :: id_cg1 = -1 ! diag handle for mode-1 speed
Expand Down

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