PUBLIC INTERFACE ~ PUBLIC ROUTINES ~ NAMELIST

Module ocean_vert_pp_mod

Contact:  Stephen Griffies
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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_parameters_mod
     ocean_types_mod
 ocean_vert_util_mod
 ocean_workspace_mod

PUBLIC INTERFACE

ocean_vert_pp_init:
vert_mix_pp:
ri_for_pp:

PUBLIC ROUTINES

  1. ocean_vert_pp_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. vert_mix_pp

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


  3. ri_for_pp

    DESCRIPTION
    Compute richardson number for the pp scheme


NAMELIST

&ocean_vert_pp_nml

use_this_module
Must be true to use this module. Default is false.
[logical]
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]

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

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.

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