Hi Forum,
In my model domain, there are two open boundaries, in South and East. My model blows up When I use the boundary conditions available for the variables zeta, ubar and vbar. The model blows up with all combinations like Cha,Che for zeta and Shc, Red for 2D momentum. The problem is only for the eastern boundary, in the southern boundary there is no issue and also model runs well when I choose Clo option for zeta, and 2D momentum. Here is my present Lateral Boundary Conditions
LBC(isFsur) == Clo Cha Che Clo ! free-surface
LBC(isUbar) == Clo Fla Shc Clo ! 2D U-momentum
LBC(isVbar) == Clo Fla Shc Clo ! 2D V-momentum
LBC(isUvel) == Clo RadNud RadNud Clo ! 3D U-momentum
LBC(isVvel) == Clo RadNud RadNud Clo ! 3D V-momentum
LBC(isMtke) == Clo Red Red Clo ! mixing TKE
LBC(isTvar) == Clo RadNud RadNud Clo \ ! temperature
Clo RadNud RadNud Clo ! salinity
Am I doing anything wrong here? I would be grateful if anybody can give suggesitons
Problem with Lateral Boundary Conditions
Re: Problem with Lateral Boundary Conditions
Well, you don't tell us how the model blows up in the east - a picture might help. You also don't tell us how you are providing the boundary values for ubar/vbar/zeta. Is this a tidal problem?
Valid options for the Mtke boundary are radiation, gradient and closed. There is no global "else" there. Doesn't matter which you have if you are using LMD_MIXING, though. Are you?
Valid options for the Mtke boundary are radiation, gradient and closed. There is no global "else" there. Doesn't matter which you have if you are using LMD_MIXING, though. Are you?
Re: Problem with Lateral Boundary Conditions
Hi Kate,
Thanks for the reply, Sorry for the missing details. I am using the Boundary files created by Romstools and it derives values of T and S from WOA and calculates zeta, ubar, vbar etc for the boundaries(As I understand!!). Presently I am not using tides in my model. Model blows up with extreme zeta values(upto 100m) in the land boundaries of whole domain. Model runs with the following configuration
Lateral Boundary Conditions: NLM
============================
Variable Grid West Edge South Edge East Edge North Edge
--------- ---- ---------- ---------- ---------- ----------
zeta 1 Closed Chapman Imp Closed Closed
ubar 1 Closed Flather Closed Closed
vbar 1 Closed Flather Closed Closed
u 1 Closed Rad + Nud Rad + Nud Closed
v 1 Closed Rad + Nud Rad + Nud Closed
temp 1 Closed Rad + Nud Rad + Nud Closed
salt 1 Closed Rad + Nud Rad + Nud Closed
Activated C-preprocessing Options:
TEST_IO1 Indian Ocean run with Bulk daily climatologcal forcing and Srelaxation
ANA_BSFLUX Analytical kinematic bottom salinity flux.
ANA_BTFLUX Analytical kinematic bottom temperature flux.
ASSUMED_SHAPE Using assumed-shape arrays.
AVERAGES Writing out time-averaged nonlinear model fields.
BULK_FLUXES Surface bulk fluxes parameterization.
CURVGRID Orthogonal curvilinear grid.
DIFF_3DCOEF Horizontal, time-dependent 3D diffusion coefficient.
DJ_GRADPS Parabolic Splines density Jacobian (Shchepetkin, 2002).
DOUBLE_PRECISION Double precision arithmetic.
EMINUSP Compute Salt Flux using E-P.
LIMIT_BSTRESS Limit bottom stress to maintain bottom velocity direction.
LMD_BKPP KPP bottom boundary layer mixing.
LMD_CONVEC LMD convective mixing due to shear instability.
LMD_DDMIX LMD double-diffusive mixing.
LMD_MIXING Large/McWilliams/Doney interior mixing.
LMD_NONLOCAL LMD convective nonlocal transport.
LMD_RIMIX LMD diffusivity due to shear instability.
LMD_SKPP KPP surface boundary layer mixing.
MASKING Land/Sea masking.
MIX_GEO_TS Mixing of tracers along geopotential surfaces.
MIX_S_UV Mixing of momentum along constant S-surfaces.
MPI MPI distributed-memory configuration.
NONLINEAR Nonlinear Model.
NONLIN_EOS Nonlinear Equation of State for seawater.
POWER_LAW Power-law shape time-averaging barotropic filter.
PROFILE Time profiling activated .
!RST_SINGLE Double precision fields in restart NetCDF file.
SALINITY Using salinity.
SRELAXATION Surface salinity relaxation as surface flux.
SOLAR_SOURCE Solar Radiation Source Term.
SOLVE3D Solving 3D Primitive Equations.
TS_C4HADVECTION Fourth-order centered horizontal advection of tracers.
TS_A4VADVECTION Fourth-order Akima vertical advection of tracers.
TS_DIF2 Harmonic mixing of tracers.
TS_DIF4 Biharmonic mixing of tracers.
TS_SMAGORINSKY Smagorinksy-like time-dependent diffusion coefficients.
UV_ADV Advection of momentum.
UV_COR Coriolis term.
UV_C4ADVECTION Fourth-order centered differences advection of momentum.
UV_QDRAG Quadratic bottom stress.
UV_VIS2 Harmonic mixing of momentum.
UV_VIS4 Biharmonic mixing of momentum.
UV_SMAGORINSKY Smagorinksy-like time-dependent viscosity coefficients.
VAR_RHO_2D Variable density barotropic mode.
VISC_GRID Horizontal viscosity coefficient scaled by grid size.
VISC_3DCOEF Horizontal, time-dependent 3D viscosity coefficient.
WET_DRY Wetting and drying activated.
Actually the eastern edge is open but zeta, ubar, vbar blows up with options other than Clo. Am I do anything wrong?
Thanks for the reply, Sorry for the missing details. I am using the Boundary files created by Romstools and it derives values of T and S from WOA and calculates zeta, ubar, vbar etc for the boundaries(As I understand!!). Presently I am not using tides in my model. Model blows up with extreme zeta values(upto 100m) in the land boundaries of whole domain. Model runs with the following configuration
Lateral Boundary Conditions: NLM
============================
Variable Grid West Edge South Edge East Edge North Edge
--------- ---- ---------- ---------- ---------- ----------
zeta 1 Closed Chapman Imp Closed Closed
ubar 1 Closed Flather Closed Closed
vbar 1 Closed Flather Closed Closed
u 1 Closed Rad + Nud Rad + Nud Closed
v 1 Closed Rad + Nud Rad + Nud Closed
temp 1 Closed Rad + Nud Rad + Nud Closed
salt 1 Closed Rad + Nud Rad + Nud Closed
Activated C-preprocessing Options:
TEST_IO1 Indian Ocean run with Bulk daily climatologcal forcing and Srelaxation
ANA_BSFLUX Analytical kinematic bottom salinity flux.
ANA_BTFLUX Analytical kinematic bottom temperature flux.
ASSUMED_SHAPE Using assumed-shape arrays.
AVERAGES Writing out time-averaged nonlinear model fields.
BULK_FLUXES Surface bulk fluxes parameterization.
CURVGRID Orthogonal curvilinear grid.
DIFF_3DCOEF Horizontal, time-dependent 3D diffusion coefficient.
DJ_GRADPS Parabolic Splines density Jacobian (Shchepetkin, 2002).
DOUBLE_PRECISION Double precision arithmetic.
EMINUSP Compute Salt Flux using E-P.
LIMIT_BSTRESS Limit bottom stress to maintain bottom velocity direction.
LMD_BKPP KPP bottom boundary layer mixing.
LMD_CONVEC LMD convective mixing due to shear instability.
LMD_DDMIX LMD double-diffusive mixing.
LMD_MIXING Large/McWilliams/Doney interior mixing.
LMD_NONLOCAL LMD convective nonlocal transport.
LMD_RIMIX LMD diffusivity due to shear instability.
LMD_SKPP KPP surface boundary layer mixing.
MASKING Land/Sea masking.
MIX_GEO_TS Mixing of tracers along geopotential surfaces.
MIX_S_UV Mixing of momentum along constant S-surfaces.
MPI MPI distributed-memory configuration.
NONLINEAR Nonlinear Model.
NONLIN_EOS Nonlinear Equation of State for seawater.
POWER_LAW Power-law shape time-averaging barotropic filter.
PROFILE Time profiling activated .
!RST_SINGLE Double precision fields in restart NetCDF file.
SALINITY Using salinity.
SRELAXATION Surface salinity relaxation as surface flux.
SOLAR_SOURCE Solar Radiation Source Term.
SOLVE3D Solving 3D Primitive Equations.
TS_C4HADVECTION Fourth-order centered horizontal advection of tracers.
TS_A4VADVECTION Fourth-order Akima vertical advection of tracers.
TS_DIF2 Harmonic mixing of tracers.
TS_DIF4 Biharmonic mixing of tracers.
TS_SMAGORINSKY Smagorinksy-like time-dependent diffusion coefficients.
UV_ADV Advection of momentum.
UV_COR Coriolis term.
UV_C4ADVECTION Fourth-order centered differences advection of momentum.
UV_QDRAG Quadratic bottom stress.
UV_VIS2 Harmonic mixing of momentum.
UV_VIS4 Biharmonic mixing of momentum.
UV_SMAGORINSKY Smagorinksy-like time-dependent viscosity coefficients.
VAR_RHO_2D Variable density barotropic mode.
VISC_GRID Horizontal viscosity coefficient scaled by grid size.
VISC_3DCOEF Horizontal, time-dependent 3D viscosity coefficient.
WET_DRY Wetting and drying activated.
Actually the eastern edge is open but zeta, ubar, vbar blows up with options other than Clo. Am I do anything wrong?
Re: Problem with Lateral Boundary Conditions
Have you looked at your boundary files? That's what I would do. Just fire up ncview and see what's in there.
That said, what you get from WOA is going to be a monthly climatology, right? We gave up on using such boundary conditions a long, long time ago, finding that global reanalysis products give better results. I have access to 5-daily SODA fields for some years and daily HYCOM fields for more recent years. What is your ultimate goal for this domain? A realistic hindcast? Getting familiar with ROMS?
That said, what you get from WOA is going to be a monthly climatology, right? We gave up on using such boundary conditions a long, long time ago, finding that global reanalysis products give better results. I have access to 5-daily SODA fields for some years and daily HYCOM fields for more recent years. What is your ultimate goal for this domain? A realistic hindcast? Getting familiar with ROMS?
Re: Problem with Lateral Boundary Conditions
Hi Kate,
Thanks again for your suggestions, I checked my boundary files and found out that there is some unacceptable values for zeta (~10m Maximum). I would change my boundary to analysis products and I am trying towards a realistic hindcast indeed. In that case what could be the reasonable combinations of LBC? Can you give some insights?
Thanks again for your suggestions, I checked my boundary files and found out that there is some unacceptable values for zeta (~10m Maximum). I would change my boundary to analysis products and I am trying towards a realistic hindcast indeed. In that case what could be the reasonable combinations of LBC? Can you give some insights?
Re: Problem with Lateral Boundary Conditions
You've tried both the "Cha Fla" combo and the "Che Shc" combo. I haven't noticed a huge difference when going from the former to the latter. Those are the right things to try once you get your boundary file in order. Plus the RadNud for the 3-D fields.
Re: Problem with Lateral Boundary Conditions
Hi Kate,
Thanks for your points. I would like to know one more thing with the same model configuration, although it is not under the Post subject. The salinity values in some parts of my domain goes high about 38PSU where the climatological values are about 35PSU when I switch off SRELAXATION and activate BULK_FLUXES. Is it advisable to use SRELAXATION, although I have point sources for temperature and salinity like rivers in my domain? Or any other way to control Salinity?
Thanks for your points. I would like to know one more thing with the same model configuration, although it is not under the Post subject. The salinity values in some parts of my domain goes high about 38PSU where the climatological values are about 35PSU when I switch off SRELAXATION and activate BULK_FLUXES. Is it advisable to use SRELAXATION, although I have point sources for temperature and salinity like rivers in my domain? Or any other way to control Salinity?
Re: Problem with Lateral Boundary Conditions
There is SRELAXATION which imposes only SSS nudging, no other surface salt fluxes and SCORRECTION which imposes both SSS nudging and other surface salt fluxes. I use the latter. However, you should also dig deeper to see where that SSS of 38 is coming from. Is it in a region of large evaporation or is something else going wrong? What are the surface salt fluxes coming from BULK_FLUXES? Are they sensible?
Re: Problem with Lateral Boundary Conditions
Hi Kate,
As you suggested, I checked the fluxes, by writing along with the output average files and found that in the region where high salinity is observed, the time-averaged surface net salt flux, (E-P)*SALT: is always positive throughout the year. The following are the maximum and minimum values of heat fluxes for a complete year, the extremes of heat flux goes very high. What could be the solution? How can I bring down those extremes?
time-averaged surface net salt flux, (E-P)*SALT ;units: meter second-1; min=-2.02356e-06 max=6.24946e-07
time-averaged evaporation rate: units : kilogram meter-2 second-1 ; min=-8.3577e-05 max=0.000175504
time-averaged net sensible heat flux: watt meter-2 ; min=-171.864 max=153.387
time-averaged surface net heat flux: watt meter-2 ; min=-590.681 max=491.342
As you suggested, I checked the fluxes, by writing along with the output average files and found that in the region where high salinity is observed, the time-averaged surface net salt flux, (E-P)*SALT: is always positive throughout the year. The following are the maximum and minimum values of heat fluxes for a complete year, the extremes of heat flux goes very high. What could be the solution? How can I bring down those extremes?
time-averaged surface net salt flux, (E-P)*SALT ;units: meter second-1; min=-2.02356e-06 max=6.24946e-07
time-averaged evaporation rate: units : kilogram meter-2 second-1 ; min=-8.3577e-05 max=0.000175504
time-averaged net sensible heat flux: watt meter-2 ; min=-171.864 max=153.387
time-averaged surface net heat flux: watt meter-2 ; min=-590.681 max=491.342