PUBLIC INTERFACE ~ PUBLIC DATA ~ PUBLIC ROUTINES ~ NAMELIST ~ DIAGNOSTIC FIELDS ~ ERROR MESSAGES ~ REFERENCES ~ NOTES

Module ocean_lap_friction_mod

Contact:  R. C. Pacanowski
Reviewers:  Stephen M. Griffies
Change History: WebCVS Log


OVERVIEW

This module computes the thickness weighted acceleration for horizontal velocity arising from horizontal Laplacian friction.

This module computes the thickness weighted time tendency for horizontal velocity arising from horizontal Laplacian friction. The viscosity used to determine the strength of the tendency can be a general function of space yet it is constant in time. A namelist option exists that determines this viscosity as a local function of the grid spacing.


OTHER MODULES USED

      constants_mod
diag_manager_mod
fms_mod
mpp_domains_mod
mpp_mod
ocean_types_mod
ocean_domains_mod
ocean_operators_mod

PUBLIC INTERFACE

ocean_lap_friction_init:
horz_lap_friction:
horz_lap_viscosity_check:
horz_lap_reynolds_check:


PUBLIC DATA

None.


PUBLIC ROUTINES

  1. ocean_lap_friction_init

    DESCRIPTION
    Initialize the horizontal Laplacian friction module by registering fields for diagnostic output and performing some numerical checks to see that viscosity is set appropriately.


  2. horz_lap_friction

    DESCRIPTION
    This function computes the thickness weighted time tendency for horizontal velocity from horizontal Laplacian friction.


  3. horz_lap_viscosity_check

    DESCRIPTION
    Subroutine to perform linear stability check for the Laplacian operator given a value for the horizontal biharmonic viscosity.


  4. horz_lap_reynolds_check

    DESCRIPTION
    Subroutine to compute the LLaplacian grid Reynolds number. Large Reynolds numbers indicate regions where solution may experience some grid noise due to lack of enough horizontal friction.



NAMELIST

&ocean_lap_friction_const_nml

lap_friction_on
Must be true to use this module.
[logical]
alap
This is the value for the space-time constant Laplacian viscosity.
[real, units: m^2/sec]
velocity_mix_micom
If .true., then the viscosity is set according to a velocity scale times the cube of the grid spacing. It is based on an approach recommended by Eric Chassignet that is used in the Miami Isopycnal Model.
[logical]
vel_micom
Velocity scale that is used for computing the MICOM viscosity.
[real, units: m/sec]


DATA SETS

None.


ERROR MESSAGES

None.


REFERENCES

  1. R. J. Murray and C. J. C. Reason, A curvilinear version of the Bryan-Cox ocean model Journal Computational Physics (2002), vol 171, pages 1--46
  2. R.C. Pacanowski and A. Gnanadesikan, Transient response in a z-level ocean model that resolves topography with partial-cells Monthly Weather Review (1998), vol 126, pages 3248-3270


COMPILER SPECIFICS

None.


PRECOMPILER OPTIONS

None.


LOADER OPTIONS

None.


TEST PROGRAM

None.


KNOWN BUGS

None.


NOTES

The numerical implementation requires no calls to mpp_update_domains.

This scheme has been found to be faster than the Smagorinsky viscosity scheme. However, the algorithm here is less robust since it contains null modes in the terms associated with the sphericity of the earth. Hence, there may be flow configurations that are not dissipated.

The model can generally run with both Laplacian and biharmonic friction enabled at the same time. Such has been found useful for some eddying ocean simulations.


FUTURE PLANS

None.


top