Module ocean_vert_mix_coeff_mod
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
PUBLIC DATA
None.
PUBLIC ROUTINES
-
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
-
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
- 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.