(*)Fixes implementation of minimum viscosity #800
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- The minimum viscsoity was only being applied in the strain component.
The minimum with KH_BG_MIN was not applied to the tension component.
This broke isotropy of the stress tensor.
- The parameter KH_BG_MIN defaults to 0.0 which would be harmless if
viscosities are always non-negative. However, when using backscatter
the viscosity is intentionally negative and this limiter was zeroing
out the backscatter, but only in the strain component.
- I've moved the min() function to before adding in the MEKE component
which is where negative viscosities might come from.
- This does not change answers in any tests BUT will change answers for
any backscatter experiments OR where KH_BG_MIN is non-zero.
herrwang0
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Jan 15, 2025
* Add ice shelf pressure initialisation bug fix This commit adds a new parameter FRAC_DP_AT_POS_NEGATIVE_P_BUGFIX and associated bug fix. This bug occurs when TRIM_IC_FOR_P_SURF pressure initialisation is used for ice shelf, whilst in Boussinesq mode and a nonlinear equation of state. The subroutine trim_for_ice calls cut_off_column_top. This routine in Boussinesq mode calls find_depth_of_pressure_in_cell in MOM_density_integrals.F90. This subsequently calls the function frac_dp_at_pos which calls the density equation of state based on given salinity, temperature and depth, which is incorrectly converted into pressure by z position (which is negative) multiplied by g and rho0. The bug results in incorrect densities from the equation of state and therefore an imperfect initialisation of layer thicknesses and sea surface height due to the displacement of water by the ice. The bug is fixed by multiplying the pressure by -1. This commit introduces parameter FRAC_DP_AT_POS_NEGATIVE_P_BUGFIX with default value False to preserve answers. If true, the ice shelf initialisation is accurate to a high degree with a nonlinear equation of state. Answers should not change, except for the added parameter in MOM_parameter_doc. The same functions are called by a unit test in MOM_state_initialization; in this commit I set the MOM_state_initialization unit test to use the existing bug (with a false flag). * Resolve indenting and white space inconsitencies with MOM6 style for ice shelf pressure initialisation bug fix FRAC_DP_AT_POS_NEGATIVE_P_BUGFIX
ashao
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Jan 30, 2025
* Add ice shelf pressure initialisation bug fix This commit adds a new parameter FRAC_DP_AT_POS_NEGATIVE_P_BUGFIX and associated bug fix. This bug occurs when TRIM_IC_FOR_P_SURF pressure initialisation is used for ice shelf, whilst in Boussinesq mode and a nonlinear equation of state. The subroutine trim_for_ice calls cut_off_column_top. This routine in Boussinesq mode calls find_depth_of_pressure_in_cell in MOM_density_integrals.F90. This subsequently calls the function frac_dp_at_pos which calls the density equation of state based on given salinity, temperature and depth, which is incorrectly converted into pressure by z position (which is negative) multiplied by g and rho0. The bug results in incorrect densities from the equation of state and therefore an imperfect initialisation of layer thicknesses and sea surface height due to the displacement of water by the ice. The bug is fixed by multiplying the pressure by -1. This commit introduces parameter FRAC_DP_AT_POS_NEGATIVE_P_BUGFIX with default value False to preserve answers. If true, the ice shelf initialisation is accurate to a high degree with a nonlinear equation of state. Answers should not change, except for the added parameter in MOM_parameter_doc. The same functions are called by a unit test in MOM_state_initialization; in this commit I set the MOM_state_initialization unit test to use the existing bug (with a false flag). * Resolve indenting and white space inconsitencies with MOM6 style for ice shelf pressure initialisation bug fix FRAC_DP_AT_POS_NEGATIVE_P_BUGFIX
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This fixes a bug that:
While this does not change any of our active tests this will change answers for experiments using KH_BG_MIN or the backscatter scheme.