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Add choice of computed or constant ocean GM gravity wave speed (AMOC PR 1/6) #4835

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merged 6 commits into from
Apr 6, 2022
Merged

Add choice of computed or constant ocean GM gravity wave speed (AMOC PR 1/6) #4835

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d46c766
add choice of computed or constant GM gravity wave speed
mark-petersen Mar 16, 2022
486b9c9
add initial definitions of lt1 and lt2
mark-petersen Mar 16, 2022
b2365dd
Update name to bclModeSpeed
mark-petersen Mar 19, 2022
91b5bac
Add explanation in comments
mark-petersen Mar 20, 2022
0195995
Update bld files with output from scripts to match changes to Registry
jonbob Apr 4, 2022
c99879a
move lt1,lt2 initialization within loop for threading
mark-petersen Apr 5, 2022
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3 changes: 2 additions & 1 deletion components/mpas-ocean/bld/build-namelist
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Expand Up @@ -580,7 +580,8 @@ add_default($nl, 'config_Redi_min_layers_diag_terms');
add_default($nl, 'config_use_GM');
add_default($nl, 'config_GM_closure');
add_default($nl, 'config_GM_constant_kappa');
add_default($nl, 'config_GM_constant_gravWaveSpeed');
add_default($nl, 'config_GM_constant_bclModeSpeed');
add_default($nl, 'config_GM_minBclModeSpeed_method');
add_default($nl, 'config_GM_spatially_variable_min_kappa');
add_default($nl, 'config_GM_spatially_variable_max_kappa');
add_default($nl, 'config_GM_spatially_variable_baroclinic_mode');
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3 changes: 2 additions & 1 deletion components/mpas-ocean/bld/build-namelist-section
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Expand Up @@ -123,7 +123,8 @@ add_default($nl, 'config_Redi_min_layers_diag_terms');
add_default($nl, 'config_use_GM');
add_default($nl, 'config_GM_closure');
add_default($nl, 'config_GM_constant_kappa');
add_default($nl, 'config_GM_constant_gravWaveSpeed');
add_default($nl, 'config_GM_constant_bclModeSpeed');
add_default($nl, 'config_GM_minBclModeSpeed_method');
add_default($nl, 'config_GM_spatially_variable_min_kappa');
add_default($nl, 'config_GM_spatially_variable_max_kappa');
add_default($nl, 'config_GM_spatially_variable_baroclinic_mode');
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3 changes: 2 additions & 1 deletion components/mpas-ocean/bld/namelist_files/namelist_defaults_mpaso.xml
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Expand Up @@ -174,7 +174,8 @@
<config_GM_constant_kappa ocn_forcing="datm_forced_restoring" ocn_grid="WCAtl12to45E2r4">600.0</config_GM_constant_kappa>
<config_GM_constant_kappa ocn_forcing="datm_forced_restoring" ocn_grid="SOwISC12to60E2r4">600.0</config_GM_constant_kappa>
<config_GM_constant_kappa ocn_forcing="datm_forced_restoring" ocn_grid="ECwISC30to60E2r1">600.0</config_GM_constant_kappa>
<config_GM_constant_gravWaveSpeed>0.3</config_GM_constant_gravWaveSpeed>
<config_GM_constant_bclModeSpeed>0.3</config_GM_constant_bclModeSpeed>
<config_GM_minBclModeSpeed_method>'constant'</config_GM_minBclModeSpeed_method>
<config_GM_spatially_variable_min_kappa>300.0</config_GM_spatially_variable_min_kappa>
<config_GM_spatially_variable_max_kappa>1800.0</config_GM_spatially_variable_max_kappa>
<config_GM_spatially_variable_baroclinic_mode>3.0</config_GM_spatially_variable_baroclinic_mode>
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14 changes: 11 additions & 3 deletions components/mpas-ocean/bld/namelist_files/namelist_definition_mpaso.xml
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Expand Up @@ -487,7 +487,7 @@ Default: Defined in namelist_defaults.xml

<entry id="config_Redi_N2_based_taper_limit_term1" type="logical"
category="Redi_isopycnal_mixing" group="Redi_isopycnal_mixing">
If true, the N2 lim iting is applied to the horizontal diffusion term
If true, the N2 limiting is applied to the horizontal diffusion term

Valid values: .true. or .false.
Default: Defined in namelist_defaults.xml
Expand Down Expand Up @@ -528,14 +528,22 @@ Valid values: MISSING POSSIBLE VALUES
Default: Defined in namelist_defaults.xml
</entry>

<entry id="config_GM_constant_gravWaveSpeed" type="real"
<entry id="config_GM_constant_bclModeSpeed" type="real"
category="GM_eddy_parameterization" group="GM_eddy_parameterization">
Gravity wave speed for the vertical stream function boundary value problem. This appears as $c$ in eqn 16a of Ferrari et al. 2010 (https://doi.org/10.1016/j.ocemod.2010.01.004).
The parameter setting for the first baroclinic mode speed for the vertical stream function boundary value problem. This appears as $c$ in eqn 16a of Ferrari et al. 2010 (https://doi.org/10.1016/j.ocemod.2010.01.004).

Valid values: Positive real numbers
Default: Defined in namelist_defaults.xml
</entry>

<entry id="config_GM_minBclModeSpeed_method" type="char*1024"
category="GM_eddy_parameterization" group="GM_eddy_parameterization">
Determines how the GM setting for the minimum of the first baroclinic mode speed is computed. If 'constant' then use config_GM_constant_bclModeSpeed. If 'computed' then compute at every edge at every time step using the Brunt-Vaisala frequency

Valid values: 'constant' and 'computed'
Default: Defined in namelist_defaults.xml
</entry>

<entry id="config_GM_spatially_variable_min_kappa" type="real"
category="GM_eddy_parameterization" group="GM_eddy_parameterization">
minimum value of bolus diffusivity for spatially variable GM schemes. Used for all choices of config_GM_closure other than 'constant'.
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8 changes: 6 additions & 2 deletions components/mpas-ocean/src/Registry.xml
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Expand Up @@ -357,10 +357,14 @@
<nml_option name="config_GM_constant_kappa" type="real" default_value="600.0" units="m^2 s^{-1}"
description="Coefficient of standard GM parametrization of eddy transport (Bolus component), $\kappa$. Only used when config_GM_closure is set to constant."
/>
<nml_option name="config_GM_constant_gravWaveSpeed" type="real" default_value="0.3" units="m/s"
description="Gravity wave speed for the vertical stream function boundary value problem. This appears as $c$ in eqn 16a of Ferrari et al. 2010 (https://doi.org/10.1016/j.ocemod.2010.01.004)."
<nml_option name="config_GM_constant_bclModeSpeed" type="real" default_value="0.3" units="m/s"
description="The parameter setting for the first baroclinic mode speed for the vertical stream function boundary value problem. This appears as $c$ in eqn 16a of Ferrari et al. 2010 (https://doi.org/10.1016/j.ocemod.2010.01.004)."
possible_values="Positive real numbers"
/>
<nml_option name="config_GM_minBclModeSpeed_method" type="character" default_value="constant" units="NA"
description="Determines how the GM setting for the minimum of the first baroclinic mode speed is computed. If 'constant' then use config_GM_constant_bclModeSpeed. If 'computed' then compute at every edge at every time step using the Brunt-Vaisala frequency"
possible_values="'constant' and 'computed'"
/>
<nml_option name="config_GM_spatially_variable_min_kappa" type="real" default_value="300.0" units="m^2 s^{-1}"
description="minimum value of bolus diffusivity for spatially variable GM schemes. Used for all choices of config_GM_closure other than 'constant'."
possible_values="values around 100s"
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42 changes: 36 additions & 6 deletions components/mpas-ocean/src/shared/mpas_ocn_gm.F
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Expand Up @@ -53,6 +53,8 @@ module ocn_gm
logical :: local_config_GM_kappa_lat_depth_variable
logical :: local_config_GM_compute_EdenGreatbatch
real(kind=RKIND) :: slopeTaperFactor, sfcTaperFactor, rediGMinitValue
real(kind=RKIND) :: local_config_GM_constant_bclModeSpeed
real(kind=RKIND) :: gm_minBclModeSpeed_constant, gm_minBclModeSpeed_compute_on

!***********************************************************************

Expand Down Expand Up @@ -132,7 +134,7 @@ subroutine ocn_GM_compute_Bolus_velocity(statePool, &
real(kind=RKIND) :: sumRi, RiTopOfEdge, zEdge, zMLD, sfcTaper
real(kind=RKIND) :: dcEdgeInv, drhoDx, drhoDT, drhoDS, dTdx, dSdx
real(kind=RKIND) :: slopeTaperUp, slopeTaperDown, sfcTaperUp, sfcTaperDown, invAreaCell
real(kind=RKIND) :: lt1, lt2
real(kind=RKIND) :: lt1, lt2, c_min
real(kind=RKIND) :: sigma, Lr, Length, L_rhines, shearEdgeInv
real(kind=RKIND), dimension(:), allocatable :: dzTop, dTdzTop, dSdzTop, k33Norm
real(kind=RKIND) :: c_Visbeck ! baroclinic wave speed from Visbeck parameterization
Expand Down Expand Up @@ -543,22 +545,37 @@ subroutine ocn_GM_compute_Bolus_velocity(statePool, &
! config_GM_spatially_variable_baroclinic_mode
if (local_config_GM_lat_variable_c2) then
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!$omp parallel
!$omp do schedule(runtime) private(k, cell1, cell2, sumN2, lt1, lt2)
!$omp do schedule(runtime) private(k, cell1, cell2, sumN2, lt1, lt2, ltSum, c_min)
do iEdge = 1, nEdges
cell1 = cellsOnEdge(1, iEdge)
cell2 = cellsOnEdge(2, iEdge)
sumN2 = 0.0

sumN2 = 0.0_RKIND
lt1 = 0.0_RKIND
lt2 = 0.0_RKIND
ltSum = epsGM
do k = minLevelEdgeBot(iEdge)+1, maxLevelEdgeTop(iEdge)-1

lt1 = 0.5_RKIND*(layerThickness(k,cell1) + layerThickness(k-1,cell1))
lt2 = 0.5_RKIND*(layerThickness(k,cell2) + layerThickness(k-1,cell2))
sumN2 = sumN2 + 0.5_RKIND*(lt1*sqrt(max(BruntVaisalaFreqTop(k,cell1),0.0_RKIND)) + &
lt2*sqrt(max(BruntVaisalaFreqTop(k,cell2),0.0_RKIND)))

ltSum = ltSum + 0.5*(lt1+lt2)
end do

cGMphaseSpeed(iEdge) = max(config_GM_constant_gravWaveSpeed, &
! Compute the minimum allowed speed of the first baroclinic mode.
! If config_GM_minBclModeSpeed_method='constant' use local_config_GM_constant_bclModeSpeed.
! If config_GM_minBclModeSpeed_method='computed' use Brunt-Vaisala frequency on this edge.
! See initialization of these variables in this modules init routine.
! The value 0.5*(lt1+lt2) is meant to be an estimate of the largest thickness
! in the column, and c_min is constructed such that we satisfy
! the condition c/N < dz. The condition is an estimate, but
! tries to insure that the streamfunction is well resolved even
! for the thickest layers.
c_min = gm_minBclModeSpeed_constant + gm_minBclModeSpeed_compute_on*max(0.01_RKIND,sumN2/ltSum*(0.5*(lt1+lt2)))

! Compute the speed of the first baroclinic mode from the Brunt-Vaisala frequency.
cGMphaseSpeed(iEdge) = max(c_min, &
sumN2/(config_GM_spatially_variable_baroclinic_mode*3.141592_RKIND))
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@vanroekel I changed the flag names to

    config_GM_constant_bclModeSpeed = 0.3
    config_GM_minBclModeSpeed_method = 'constant'

The only substantial change is the line above, but I use fixed coefficient values set on init to avoid if statements inside the loop.


end do
Expand All @@ -569,7 +586,7 @@ subroutine ocn_GM_compute_Bolus_velocity(statePool, &
!$omp parallel
!$omp do schedule(runtime)
do iEdge = 1, nEdges
cGMphaseSpeed(iEdge) = config_GM_constant_gravWaveSpeed
cGMphaseSpeed(iEdge) = local_config_GM_constant_bclModeSpeed
end do
!$omp end do
!$omp end parallel
Expand Down Expand Up @@ -910,6 +927,19 @@ subroutine ocn_GM_init(domain, err)!{{{
sfcTaperFactor = 0.0_RKIND
end if

local_config_GM_constant_bclModeSpeed = config_GM_constant_bclModeSpeed

if (config_GM_minBclModeSpeed_method=='constant') then
gm_minBclModeSpeed_compute_on = 0.0_RKIND
gm_minBclModeSpeed_constant = config_GM_constant_bclModeSpeed
elseif (config_GM_minBclModeSpeed_method=='computed') then
gm_minBclModeSpeed_compute_on = 1.0_RKIND
gm_minBclModeSpeed_constant = 0.0_RKIND
else
call mpas_log_write('config_GM_minBclModeSpeed_method must be constant or computed', &
MPAS_LOG_CRIT)
end if

RediGMinitValue = 1.0_RKIND
if (config_GM_closure == 'constant') then
local_config_GM_lat_variable_c2 = .false.
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2 changes: 1 addition & 1 deletion components/mpas-ocean/src/shared/mpas_ocn_test.F
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Expand Up @@ -316,7 +316,7 @@ subroutine ocn_init_gm_test_functions(meshPool, scratchPool)!{{{
! zBot is location we apply boundary conditions on the ODE for stream function.
zBot = zMax

L = config_GM_constant_gravWaveSpeed * sqrt(rho_sw * zMax / gravity / config_eos_linear_alpha / config_gm_analytic_temperature3)
L = config_GM_constant_bclModeSpeed * sqrt(rho_sw * zMax / gravity / config_eos_linear_alpha / config_gm_analytic_temperature3)
R = - config_GM_constant_kappa * config_gm_analytic_temperature2 * zMax / config_gm_analytic_temperature3 &
/ config_gm_analytic_ymax
c1 = R*(1-exp(-zBot/L))/(exp(zBot/L) - exp(-zBot/L))
Expand Down