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

Module ocean_polar_filter_mod

Contact:  Mike Spelman Stephen M. Griffies
Reviewers: 
Change History: WebCVS Log


OVERVIEW

Provide polar filtering of fields for use with spherical grid. Set up only for filtering tracers with 1D domain decomposition.

This module provides polar filtering of tracers for use with spherical coordinate grids. Should not be used with non-spherical grids. This code is provided for legacy purposes to allow modelers the opportunity to test their older spherical models in mom4 prior to moving to a generalized horizontal grid, such as the tripolar.

Polar filtering has many well known problems, especially when filtering the velocity and/or free surface fields. Hence, this module only provides for filtering the tracer field. Even so, its use is discouraged for those building new ocean model configurations.

This scheme has been implemented ONLY for cases with 1D domain decomposition (constant latitude rows). Paralellization in 2D is not available with this implementation.

There are two methods for polar filtering: (1) polar filter the time tendencies (as in mom3) and (2) polar filtering the fields themselves (as in mom1). The mom1 method is preferred at GFDL when running with an ice model.



OTHER MODULES USED

   axis_utils_mod
constants_mod
diag_manager_mod
fms_mod
mpp_domains_mod
mpp_mod
ocean_domains_mod
ocean_types_mod

PUBLIC INTERFACE

ocean_polar_filter_init:
Initialize polar filtering module.
polar_filter_tracers:
set up input needed for symmetric finite impulse response filtering at the specified high latitude row.
fast_fir:
Finite impulse response filter with [.25, .5, .25] weights using built in symmetric boundary conditions at land
set_polar_filtering_indices:
Set up model indices for filtering polar latitudes


PUBLIC DATA

None.


PUBLIC ROUTINES

  1. ocean_polar_filter_init

    DESCRIPTION


  2. polar_filter_tracers

    DESCRIPTION


  3. fast_fir

    DESCRIPTION
    input:

    f = functions to be filtered

    rmask = mask. must be (1.0,0.0) on (ocean,land) points

    num = number of filter applications

    output:

    f = filtered quantities

    author: r.c.pacanowski e-mail Ronald.Pacanowski@noaa.gov



  4. set_polar_filtering_indices

    DESCRIPTION



NAMELIST

&ocean_polar_filter_nml

polar_filter_on
Must be true to use this module.
[logical]
polar_filter_field
Polar filter the tracer field (default method)
[logical]
polar_filter_tendency
Polar filter the time tendency of tracers
[logical]
rjfrst
Southern latitude below which apply no filtering
[real]
filter_reflat_s
Southern latitude to which we reference filtering
[real]
filter_reflat_n
Northern latitude to which we reference filtering
[real]


DATA SETS

None.


ERROR MESSAGES

None.


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