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

Module ocean_vert_mix_coeff_mod

Contact:  R. C. Pacanowski
Reviewers: 
Change History: WebCVS Log


OVERVIEW

Vertical viscosity and diffusivity according Pacanowski and Philander (1981)

This module computes vertical viscosity and diffusivity according to Pacanowski and Philander (1981). This scheme is most effective for studies of the tropical circulation. It computes the vertical mixing coefficient based on the Richardson number.


OTHER MODULES USED

      constants_mod
diag_manager_mod
fms_mod
mpp_mod
ocean_density_mod
ocean_domains_mod
ocean_types_mod
ocean_vert_mix_mod
ocean_workspace_mod

PUBLIC INTERFACE

ocean_vert_mix_coeff_init:
vertical_mix_coeff:


PUBLIC DATA

None.


PUBLIC ROUTINES

  1. ocean_vert_mix_coeff_init

    DESCRIPTION
    Initialization for the Pacanowski/Philander vertical mixing scheme

    input:

    dzt = thickness of vertical levels (m)

    nk = number of vertical levels

    yt = latitude of grid points (deg)

    nj = number of latitudes

    error = logical to signal problems

    output:

    wndmix = min value for mixing at surface to simulate high freq

    wind mixing (if absent in forcing). (m^2/sec)

    fricmx = maximum mixing (m^2/sec)

    diff_cbt_back_pp = background "diff_cbt" (m^2/sec)

    visc_cbu_back_pp = background "visc_cbu" (m^2/sec)

    diff_cbt_limit = largest "diff_cbt" (m^2/sec)

    visc_cbu_limit = largest "visc_cbu" (m^2/sec)

    error = true if some inconsistency was found



  2. vertical_mix_coeff

    DESCRIPTION
    This subroutine computes the vertical diffusivity and viscosity according to the Pacanowski and Philander scheme. Mixing coefficients are space and time dependent.

    inputs:

    nk = number of vertical levels
    grav = gravity (m/sec^2)
    fricmx = max viscosity (m^2/sec)
    wndmix = min viscosity at bottom of 1st level to simulate
    missing high frequency windstress components (m^2/sec)
    visc_cbu_back_pp = background "visc_cbu" (m^2/sec)
    diff_cbt_back_pp = background "diff_cbt" (m^2/sec)
    visc_cbu_limit = largest "visc_cbu" in regions of gravitational
    instability (m^2/sec)
    diff_cbt_limit = largest "diff_cbt" in regions of gravitational
    instability (m^2/sec)
    riu = richardson number at bottom of U cells
    rit = richardson number at bottom of T cells
    outputs:

    visc_cbu = viscosity at bottom of U cells (m^2/s)
    diff_cbt = diffusion at bottom of T cells (m^2/s)




NAMELIST

&ocean_vert_mix_coeff_pp_nml

wndmix
Minimum viscosity at bottom of 1st level to simulate missing high frequency windstress components.
[real, units: m^2/sec]
fricmx
Maximum mixing
[real, units: m^2/sec]
diff_cbt_back_pp
Space-time independent background vertical diffusivity thought to be that arising from internal waves. Note that if using Bryan-Lewis background diffusivity, then should set diff_cbt_back_pp=0.0.
[real, units: m^2/sec]
visc_cbu_back_pp
Background vertical viscosity
[real, units: m^2/sec]


DATA SETS

None.


ERROR MESSAGES

None.


REFERENCES

  1. R.C. Pacanowski and G. Philander Parametrization of vertical mixing in numerical models of the tropical ocean Journal of Physical Oceanography (1981) vol 11, pages 1442--1451


COMPILER SPECIFICS

None.


PRECOMPILER OPTIONS

None.


LOADER OPTIONS

None.


TEST PROGRAM

None.


KNOWN BUGS

None.


NOTES

This parameterization was designed for equatorial models and may not do a good job in mid or high latitudes. Simulations in these regions (where vertical shear is small) are improved with the addition of solar short wave penetration into the ocean which reduces buoyancy and enhances vertical mixing.


FUTURE PLANS

None.


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