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+Add cons_temp_to_pot_temp & abs_saln_to_prac_saln
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  This commit adds new functionality to the MOM_EOS module to support the
dimensional rescaling of temperatures and salinities.

 - Added the new routines cons_temp_to_pot_temp and abs_saln_to_prac_saln to
   convert between forms of temperature and salinity variables, respectively.
   These work on arrays of rescaled variables.

 - Added the new optional argument scale_from_EOS to calculate_TFreeze_scalar,
   to indicate that this routine should use the unit scaling stored in their
   EOS_type arguments.

 - Also corrected some comments throughout MOM_EOS.F90.

All answers are bitwise identical, but there are new public interfaces.
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@Hallberg-NOAA
Hallberg-NOAA committed May 16, 2022
1 parent b3c41b1 commit 079fd3e
Showing 1 changed file with 132 additions and 27 deletions.
159 changes: 132 additions & 27 deletions src/equation_of_state/MOM_EOS.F90
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,8 @@ module MOM_EOS
public calculate_TFreeze
public convert_temp_salt_for_TEOS10
public extract_member_EOS
public cons_temp_to_pot_temp
public abs_saln_to_prac_saln
public gsw_sp_from_sr
public gsw_pt_from_ct
public query_compressible
Expand Down Expand Up @@ -162,7 +164,7 @@ module MOM_EOS

!> Calls the appropriate subroutine to calculate density of sea water for scalar inputs.
!! If rho_ref is present, the anomaly with respect to rho_ref is returned. The pressure and
!! density can be rescaled with the US. If both the US and scale arguments are present the density
!! density can be rescaled with the values stored in EOS. If the scale argument is present the density
!! scaling uses the product of the two scaling factors.
subroutine calculate_density_scalar(T, S, pressure, rho, EOS, rho_ref, scale)
real, intent(in) :: T !< Potential temperature referenced to the surface [C ~> degC]
Expand All @@ -172,7 +174,7 @@ subroutine calculate_density_scalar(T, S, pressure, rho, EOS, rho_ref, scale)
type(EOS_type), intent(in) :: EOS !< Equation of state structure
real, optional, intent(in) :: rho_ref !< A reference density [R ~> kg m-3]
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale output density in
!! combination with scaling given by US [various]
!! combination with scaling stored in EOS [various]

real :: Ta(1) ! An array of temperatures [degC]
real :: Sa(1) ! An array of salinities [ppt]
Expand Down Expand Up @@ -212,7 +214,7 @@ subroutine calculate_stanley_density_scalar(T, S, pressure, Tvar, TScov, Svar, r
type(EOS_type), intent(in) :: EOS !< Equation of state structure
real, optional, intent(in) :: rho_ref !< A reference density [R ~> kg m-3].
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale output density in
!! combination with scaling given by US [various]
!! combination with scaling stored in EOS [various]
! Local variables
real :: d2RdTT, d2RdST, d2RdSS, d2RdSp, d2RdTp ! Second derivatives of density wrt T,S,p
real :: p_scale ! A factor to convert pressure to units of Pa [Pa T2 R-1 L-2 ~> 1]
Expand Down Expand Up @@ -350,7 +352,7 @@ subroutine calculate_density_1d(T, S, pressure, rho, EOS, dom, rho_ref, scale)
!! into account that arrays start at 1.
real, optional, intent(in) :: rho_ref !< A reference density [R ~> kg m-3]
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale density
!! in combination with scaling given by US [various]
!! in combination with scaling stored in EOS [various]
! Local variables
real :: rho_scale ! A factor to convert density from kg m-3 to the desired units [R m3 kg-1 ~> 1]
real, dimension(size(rho)) :: pres ! Pressure converted to [Pa]
Expand Down Expand Up @@ -407,7 +409,7 @@ subroutine calculate_stanley_density_1d(T, S, pressure, Tvar, TScov, Svar, rho,
!! into account that arrays start at 1.
real, optional, intent(in) :: rho_ref !< A reference density [R ~> kg m-3]
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale density
!! in combination with scaling given by US [various]
!! in combination with scaling stored in EOS [various]
! Local variables
real :: rho_scale ! A factor to convert density from kg m-3 to the desired units [R m3 kg-1 ~> 1]
real :: T2_scale ! A factor to convert temperature variance to units of degC2 [degC2 C-2 ~> 1]
Expand Down Expand Up @@ -486,7 +488,7 @@ subroutine calculate_spec_vol_array(T, S, pressure, specvol, start, npts, EOS, s
type(EOS_type), intent(in) :: EOS !< Equation of state structure
real, optional, intent(in) :: spv_ref !< A reference specific volume [m3 kg-1]
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale specific
!! volume in combination with scaling given by US [various]
!! volume in combination with scaling stored in EOS [various]

real, dimension(size(specvol)) :: rho ! Density [kg m-3]
integer :: j
Expand Down Expand Up @@ -529,7 +531,7 @@ subroutine calc_spec_vol_scalar(T, S, pressure, specvol, EOS, spv_ref, scale)
type(EOS_type), intent(in) :: EOS !< Equation of state structure
real, optional, intent(in) :: spv_ref !< A reference specific volume [R-1 ~> m3 kg-1]
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale specific
!! volume in combination with scaling given by US [various]
!! volume in combination with scaling stored in EOS [various]

real, dimension(1) :: Ta ! Rescaled single element array version of temperature [degC]
real, dimension(1) :: Sa ! Rescaled single element array version of salinity [ppt]
Expand Down Expand Up @@ -568,7 +570,7 @@ subroutine calc_spec_vol_1d(T, S, pressure, specvol, EOS, dom, spv_ref, scale)
real, optional, intent(in) :: spv_ref !< A reference specific volume [R-1 ~> m3 kg-1]
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale
!! output specific volume in combination with
!! scaling given by US [various]
!! scaling stored in EOS [various]
! Local variables
real, dimension(size(T)) :: pres ! Pressure converted to [Pa]
real, dimension(size(T)) :: Ta ! Temperature converted to [degC]
Expand Down Expand Up @@ -610,32 +612,45 @@ end subroutine calc_spec_vol_1d


!> Calls the appropriate subroutine to calculate the freezing point for scalar inputs.
subroutine calculate_TFreeze_scalar(S, pressure, T_fr, EOS, pres_scale)
real, intent(in) :: S !< Salinity [ppt]
real, intent(in) :: pressure !< Pressure, in [Pa] or [R L2 T-2 ~> Pa] depending on pres_scale
real, intent(out) :: T_fr !< Freezing point potential temperature referenced
!! to the surface [degC]
type(EOS_type), intent(in) :: EOS !< Equation of state structure
subroutine calculate_TFreeze_scalar(S, pressure, T_fr, EOS, pres_scale, scale_from_EOS)
real, intent(in) :: S !< Salinity, [ppt] or [Z ~> ppt] depending on scale_from_EOS
real, intent(in) :: pressure !< Pressure, in [Pa] or [R L2 T-2 ~> Pa] depending on
!! pres_scale or scale_from_EOS
real, intent(out) :: T_fr !< Freezing point potential temperature referenced to the
!! surface [degC] or [degC ~> C] depending on scale_from_EOS
type(EOS_type), intent(in) :: EOS !< Equation of state structure
real, optional, intent(in) :: pres_scale !< A multiplicative factor to convert pressure
!! into Pa [Pa T2 R-1 L-2 ~> 1].
!! into Pa [Pa T2 R-1 L-2 ~> 1].
logical, optional, intent(in) :: scale_from_EOS !< If present true use the dimensional scaling
!! factors stored in EOS. Omission is the same .false.

! Local variables
real :: p_scale ! A factor to convert pressure to units of Pa.
real :: p_scale ! A factor to convert pressure to units of Pa [Pa T2 R-1 L-2 ~> 1]
real :: S_scale ! A factor to convert salinity to units of ppt [ppt S-1 ~> 1]

p_scale = 1.0 ; if (present(pres_scale)) p_scale = pres_scale
p_scale = 1.0 ; S_scale = 1.0
if (present(pres_scale)) p_scale = pres_scale
if (present(scale_from_EOS)) then ; if (scale_from_EOS) then
p_scale = EOS%RL2_T2_to_Pa
S_scale = EOS%S_to_ppt
endif ; endif

select case (EOS%form_of_TFreeze)
case (TFREEZE_LINEAR)
call calculate_TFreeze_linear(S, p_scale*pressure, T_fr, EOS%TFr_S0_P0, &
call calculate_TFreeze_linear(S_scale*S, p_scale*pressure, T_fr, EOS%TFr_S0_P0, &
EOS%dTFr_dS, EOS%dTFr_dp)
case (TFREEZE_MILLERO)
call calculate_TFreeze_Millero(S, p_scale*pressure, T_fr)
call calculate_TFreeze_Millero(S_scale*S, p_scale*pressure, T_fr)
case (TFREEZE_TEOS10)
call calculate_TFreeze_teos10(S, p_scale*pressure, T_fr)
call calculate_TFreeze_teos10(S_scale*S, p_scale*pressure, T_fr)
case default
call MOM_error(FATAL, "calculate_TFreeze_scalar: form_of_TFreeze is not valid.")
end select

if (present(scale_from_EOS)) then ; if (scale_from_EOS) then
T_fr = EOS%degC_to_C * T_fr
endif ; endif

end subroutine calculate_TFreeze_scalar

!> Calls the appropriate subroutine to calculate the freezing point for a 1-D array.
Expand Down Expand Up @@ -760,7 +775,7 @@ subroutine calculate_density_derivs_array(T, S, pressure, drho_dT, drho_dS, star
integer, intent(in) :: npts !< The number of values to calculate
type(EOS_type), intent(in) :: EOS !< Equation of state structure
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale density
!! in combination with scaling given by US [various]
!! in combination with scaling stored in EOS [various]

! Local variables
integer :: j
Expand Down Expand Up @@ -802,7 +817,7 @@ subroutine calculate_density_derivs_1d(T, S, pressure, drho_dT, drho_dS, EOS, do
integer, dimension(2), optional, intent(in) :: dom !< The domain of indices to work on, taking
!! into account that arrays start at 1.
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale density
!! in combination with scaling given by US [various]
!! in combination with scaling stored in EOS [various]
! Local variables
real, dimension(size(drho_dT)) :: pres ! Pressure converted to [Pa]
real, dimension(size(drho_dT)) :: Ta ! Temperature converted to [degC]
Expand Down Expand Up @@ -855,7 +870,7 @@ subroutine calculate_density_derivs_scalar(T, S, pressure, drho_dT, drho_dS, EOS
!! determined by the optional scale argument
type(EOS_type), intent(in) :: EOS !< Equation of state structure
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale density
!! in combination with scaling given by US [various]
!! in combination with scaling stored in EOS [various]
! Local variables
real :: rho_scale ! A factor to convert density from kg m-3 to the desired units [R m3 kg-1 ~> 1]
real :: dRdT_scale ! A factor to convert drho_dT to the desired units [R degC m3 C-1 kg-1 ~> 1]
Expand Down Expand Up @@ -911,7 +926,7 @@ subroutine calculate_density_second_derivs_1d(T, S, pressure, drho_dS_dS, drho_d
integer, dimension(2), optional, intent(in) :: dom !< The domain of indices to work on, taking
!! into account that arrays start at 1.
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale density
!! in combination with scaling given by US [various]
!! in combination with scaling stored in EOS [various]
! Local variables
real, dimension(size(T)) :: pres ! Pressure converted to [Pa]
real, dimension(size(T)) :: Ta ! Temperature converted to [degC]
Expand Down Expand Up @@ -1007,7 +1022,7 @@ subroutine calculate_density_second_derivs_scalar(T, S, pressure, drho_dS_dS, dr
!! [T2 C-1 L-2 ~> kg m-3 degC-1 Pa-1]
type(EOS_type), intent(in) :: EOS !< Equation of state structure
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale density
!! in combination with scaling given by US [various]
!! in combination with scaling stored in EOS [various]
! Local variables
real :: rho_scale ! A factor to convert density from kg m-3 to the desired units [R m3 kg-1 ~> 1]
real :: p_scale ! A factor to convert pressure to units of Pa [Pa T2 R-1 L-2 ~> 1]
Expand Down Expand Up @@ -1123,7 +1138,7 @@ subroutine calc_spec_vol_derivs_1d(T, S, pressure, dSV_dT, dSV_dS, EOS, dom, sca
integer, dimension(2), optional, intent(in) :: dom !< The domain of indices to work on, taking
!! into account that arrays start at 1.
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale specific
!! volume in combination with scaling given by US [various]
!! volume in combination with scaling stored in EOS [various]

! Local variables
real, dimension(size(T)) :: pres ! Pressure converted to [Pa]
Expand Down Expand Up @@ -1433,7 +1448,8 @@ logical function query_compressible(EOS)
query_compressible = EOS%compressible
end function query_compressible

!> Initializes EOS_type by allocating and reading parameters
!> Initializes EOS_type by allocating and reading parameters. The scaling factors in
!! US are stored in EOS for later use.
subroutine EOS_init(param_file, EOS, US)
type(param_file_type), intent(in) :: param_file !< Parameter file structure
type(EOS_type), intent(inout) :: EOS !< Equation of state structure
Expand Down Expand Up @@ -1630,6 +1646,95 @@ subroutine convert_temp_salt_for_TEOS10(T, S, HI, kd, mask_z, EOS)
enddo ; enddo ; enddo
end subroutine convert_temp_salt_for_TEOS10


!> Converts an array of conservative temperatures to potential temperatures. The input arguments
!! use the dimesionally rescaling as specified within the EOS type. The output potential
!! temperature uses this same scaling, but this can be replaced by the factor given by scale.
subroutine cons_temp_to_pot_temp(T, S, poTemp, EOS, dom, scale)
real, dimension(:), intent(in) :: T !< Conservative temperature [C ~> degC]
real, dimension(:), intent(in) :: S !< Absolute salinity [S ~> ppt]
real, dimension(:), intent(inout) :: poTemp !< The potential temperature with a reference pressure
!! of 0 Pa, [C ~> degC]
type(EOS_type), intent(in) :: EOS !< Equation of state structure
integer, dimension(2), optional, intent(in) :: dom !< The domain of indices to work on, taking
!! into account that arrays start at 1.
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale the output
!! potential temperature in place of with scaling stored
!! in EOS. A value of 1.0 returns temperatures in [degC],
!! while the default is equivalent to EOS%degC_to_C.

! Local variables
real, dimension(size(T)) :: Ta ! Temperature converted to [degC]
real, dimension(size(S)) :: Sa ! Salinity converted to [ppt]
real :: T_scale ! A factor to convert potential temperature from degC to the desired units [C degC-1 ~> 1]
integer :: i, is, ie

if (present(dom)) then
is = dom(1) ; ie = dom(2)
else
is = 1 ; ie = size(T)
endif

if ((EOS%C_to_degC == 1.0) .and. (EOS%S_to_ppt == 1.0)) then
poTemp(is:ie) = gsw_pt_from_ct(S(is:ie), T(is:ie))
else
do i=is,ie
Ta(i) = EOS%C_to_degC * T(i)
Sa(i) = EOS%S_to_ppt * S(i)
enddo
poTemp(is:ie) = gsw_pt_from_ct(Sa(is:ie), Ta(is:ie))
endif

T_scale = EOS%degC_to_C
if (present(scale)) T_scale = scale
if (T_scale /= 1.0) then ; do i=is,ie
poTemp(i) = T_scale * poTemp(i)
enddo ; endif

end subroutine cons_temp_to_pot_temp


!> Converts an array of absolute salinity to practical salinity. The input arguments
!! use the dimesionally rescaling as specified within the EOS type. The output potential
!! temperature uses this same scaling, but this can be replaced by the factor given by scale.
subroutine abs_saln_to_prac_saln(S, prSaln, EOS, dom, scale)
real, dimension(:), intent(in) :: S !< Absolute salinity [S ~> ppt]
real, dimension(:), intent(inout) :: prSaln !< Practical salinity [S ~> ppt]
type(EOS_type), intent(in) :: EOS !< Equation of state structure
integer, dimension(2), optional, intent(in) :: dom !< The domain of indices to work on, taking
!! into account that arrays start at 1.
real, optional, intent(in) :: scale !< A multiplicative factor by which to scale the output
!! practical in place of with scaling stored
!! in EOS. A value of 1.0 returns salinities in [PSU],
!! while the default is equivalent to EOS%ppt_to_S.

! Local variables
real, dimension(size(S)) :: Sa ! Salinity converted to [ppt]
real :: S_scale ! A factor to convert practical salnity from ppt to the desired units [S ppt-1 ~> 1]
integer :: i, is, ie

if (present(dom)) then
is = dom(1) ; ie = dom(2)
else
is = 1 ; ie = size(S)
endif

if ((EOS%C_to_degC == 1.0) .and. (EOS%S_to_ppt == 1.0)) then
prSaln(is:ie) = gsw_sp_from_sr(Sa(is:ie))
else
do i=is,ie ; Sa(i) = EOS%S_to_ppt * S(i) ; enddo
prSaln(is:ie) = gsw_sp_from_sr(Sa(is:ie))
endif

S_scale = EOS%ppt_to_S
if (present(scale)) S_scale = scale
if (S_scale /= 1.0) then ; do i=is,ie
prSaln(i) = S_scale * prSaln(i)
enddo ; endif

end subroutine abs_saln_to_prac_saln


!> Return value of EOS_quadrature
logical function EOS_quadrature(EOS)
type(EOS_type), intent(in) :: EOS !< Equation of state structure
Expand Down

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