mom_hybgen_regrid module reference

This module contains the hybgen regridding routines from HYCOM, with minor modifications to follow the MOM6 coding conventions.

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Data Types

hybgen_regrid_cs

Control structure containing required parameters for the hybgen coordinate generator.

Functions/Subroutines

`init_hybgen_regrid()`	Initialise a hybgen_regrid_CS control structure and store its parameters.
`write_hybgen_coord_file()`	Writes out a file containing any available data related to the vertical grid used by the MOM ocean model.
`end_hybgen_regrid()`	This subroutine deallocates memory in the control structure for the hybgen module.
`get_hybgen_regrid_params()`	This subroutine can be used to retrieve the parameters for the hybgen regrid module.
`hybgen_regrid()`	Modify the input grid to give a new vertical grid based on the HYCOM hybgen code.
`hybgen_column_init()`	Initialize some of the variables that are used for regridding or unmixing, including the stretched contraits on where the new interfaces can be.
`cushn()`	The cushion function from Bleck & Benjamin, 1992, which returns a smoothly varying but limited value that goes between dp0 and delp.
`hybgen_column_regrid()`	Create a new grid for a column of water using the Hybgen algorithm.

Detailed Description

This module contains the hybgen regridding routines from HYCOM, with minor modifications to follow the MOM6 coding conventions.

Type Documentation

type mom_hybgen_regrid/hybgen_regrid_cs

Control structure containing required parameters for the hybgen coordinate generator.

Type fields:

% min_thickness :: real Minimum thickness allowed for layers [H ~> m or kg m-2].
% nk :: integer Number of layers on the target grid.
% ref_pressure :: real Reference pressure for density calculations [R L2 T-2 ~> Pa].
% hybiso :: real Hybgen uses PCM if layer is within hybiso of target density [R ~> kg m-3].
% nsigma :: integer Number of sigma levels used by HYBGEN.
% dp00i :: real Deep isopycnal spacing minimum thickness [H ~> m or kg m-2].
% qhybrlx :: real Fractional relaxation within a regridding step [nondim].
% dp0k :: real, dimension(:), allocatable minimum deep z-layer separation [H ~> m or kg m-2]
% ds0k :: real, dimension(:), allocatable minimum shallow z-layer separation [H ~> m or kg m-2]
% coord_scale :: real A scaling factor to restores the depth coordinates to values in m [m H-1 ~> 1 or m3 kg-1].
% rho_coord_scale :: real A scaling factor to restores the denesity coordinates to values in kg m-3 [kg m-3 R-1 ~> 1].
% dpns :: real depth to start terrain following [H ~> m or kg m-2]
% dsns :: real depth to stop terrain following [H ~> m or kg m-2]
% min_dilate :: real The minimum amount of dilation that is permitted when converting target coordinates from z to z* [nondim]. This limit applies when wetting occurs.
% max_dilate :: real The maximum amount of dilation that is permitted when converting target coordinates from z to z* [nondim]. This limit applies when drying occurs.
% thkbot :: real Thickness of a bottom boundary layer, within which hybgen does something different. [H ~> m or kg m-2].
% topiso_const :: real Shallowest depth for isopycnal layers [H ~> m or kg m-2].
% target_density :: real, dimension(:), allocatable Nominal density of interfaces [R ~> kg m-3].
% dp_far_from_sfc :: real A distance that determines when an interface is suffiently far from the surface that certain adjustments can be made in the Hybgen regridding code [H ~> m or kg m-2]. In Hycom, this is set to tenm (nominally 10 m).
% dp_far_from_bot :: real A distance that determines when an interface is suffiently far from the bottom that certain adjustments can be made in the Hybgen regridding code [H ~> m or kg m-2]. In Hycom, this is set to onem (nominally 1 m).
% h_thin :: real A layer thickness below which a layer is considered to be too thin for certain adjustments to be made in the Hybgen regridding code [H ~> m or kg m-2]. In Hycom, this is set to onemm (nominally 0.001 m).
% rho_eps :: real A small nonzero density that is used to prevent division by zero in several expressions in the Hybgen regridding code [R ~> kg m-3].
% onem :: real Nominally one m in thickness units [H ~> m or kg m-2], used only in certain debugging tests.

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Function/Subroutine Documentation

subroutine mom_hybgen_regrid/init_hybgen_regrid(CS, GV, US, param_file)

Initialise a hybgen_regrid_CS control structure and store its parameters.

Parameters:

cs :: Unassociated pointer to hold the control structure
gv :: [in] Ocean vertical grid structure
us :: [in] A dimensional unit scaling type
param_file :: param_file [in] Parameter file

Call to:

mom_error_handler::mom_error mom_string_functions::slasher

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subroutine mom_hybgen_regrid/write_hybgen_coord_file(GV, CS, filepath)

Writes out a file containing any available data related to the vertical grid used by the MOM ocean model.

Parameters:

gv :: [in] The ocean’s vertical grid structure
cs :: [in] Control structure for this module
filepath :: filepath [in] The full path to the file to write

Call to:

mom_io::var_desc

Called from:

mom_regridding::write_regrid_file

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subroutine mom_hybgen_regrid/end_hybgen_regrid(CS)

This subroutine deallocates memory in the control structure for the hybgen module.

Parameters:: cs :: Coordinate control structure

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subroutine mom_hybgen_regrid/get_hybgen_regrid_params(CS, nk, ref_pressure, hybiso, nsigma, dp00i, qhybrlx, dp0k, ds0k, dpns, dsns, min_dilate, max_dilate, thkbot, topiso_const, target_density)

This subroutine can be used to retrieve the parameters for the hybgen regrid module.

Parameters:

cs :: Coordinate regridding control structure
nk :: nk [out] Number of layers on the target grid
ref_pressure :: ref_pressure [out] Reference pressure for density calculations [R L2 T-2 ~> Pa]
hybiso :: hybiso [out] Hybgen uses PCM if layer is within hybiso of target density [R ~> kg m-3]
nsigma :: nsigma [out] Number of sigma levels used by HYBGEN
dp00i :: dp00i [out] Deep isopycnal spacing minimum thickness [H ~> m or kg m-2]
qhybrlx :: qhybrlx [out] Fractional relaxation amount per timestep, 0 < qyhbrlx <= 1 [nondim]
dp0k :: dp0k [out] minimum deep z-layer separation [H ~> m or kg m-2]
ds0k :: ds0k [out] minimum shallow z-layer separation [H ~> m or kg m-2]
dpns :: dpns [out] depth to start terrain following [H ~> m or kg m-2]
dsns :: dsns [out] depth to stop terrain following [H ~> m or kg m-2]
min_dilate :: min_dilate [out] The minimum amount of dilation that is permitted when converting target coordinates from z to z* [nondim]. This limit applies when wetting occurs.
max_dilate :: max_dilate [out] The maximum amount of dilation that is permitted when converting target coordinates from z to z* [nondim]. This limit applies when drying occurs.
thkbot :: thkbot [out] Thickness of a bottom boundary layer, within which hybgen does something different. [H ~> m or kg m-2]
topiso_const :: topiso_const [out] Shallowest depth for isopycnal layers [H ~> m or kg m-2]
target_density :: target_density [out] Nominal density of interfaces [R ~> kg m-3]

Call to:

mom_error_handler::mom_error

Called from:

mom_hybgen_unmix::init_hybgen_unmix

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subroutine mom_hybgen_regrid/hybgen_regrid(G, GV, US, dp, nom_depth_H, tv, CS, dzInterface, PCM_cell)

Modify the input grid to give a new vertical grid based on the HYCOM hybgen code.

Parameters:

g :: [in] Ocean grid structure
gv :: [in] Ocean vertical grid structure
us :: [in] A dimensional unit scaling type
dp :: dp [in] Source grid layer thicknesses [H ~> m or kg m-2]
nom_depth_h :: [in] The bathymetric depth of this column
tv :: tv [in] Thermodynamics structure
cs :: [in] hybgen control structure
dzinterface :: [inout] The change in height of each interface,
pcm_cell :: [inout] If true, PCM remapping should be used in a cell.

Call to:

hybgen_column_init hybgen_column_regrid

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subroutine mom_hybgen_regrid/hybgen_column_init(nk, nsigma, dp0k, ds0k, dp00i, topiso_i_j, qhybrlx, dpns, dsns, h_tot, dilate, h_col, fixlay, qhrlx, dp0ij, dp0cum)

Initialize some of the variables that are used for regridding or unmixing, including the stretched contraits on where the new interfaces can be.

Parameters:

nk :: nk [in] The number of layers in the new grid
nsigma :: nsigma [in] The number of sigma levels
dp0k :: dp0k [in] Layer deep z-level spacing minimum thicknesses [H ~> m or kg m-2]
ds0k :: ds0k [in] Layer shallow z-level spacing minimum thicknesses [H ~> m or kg m-2]
dp00i :: dp00i [in] Deep isopycnal spacing minimum thickness [H ~> m or kg m-2]
topiso_i_j :: topiso_i_j [in] Shallowest depth for isopycnal layers [H ~> m or kg m-2]
qhybrlx :: qhybrlx [in] Fractional relaxation amount per timestep, 0 < qyhbrlx <= 1 [nondim]
h_tot :: h_tot [in] The sum of the initial layer thicknesses [H ~> m or kg m-2]
dilate :: dilate [in] A factor by which to dilate the target positions from z to z* [nondim]
h_col :: h_col [in] Initial layer thicknesses [H ~> m or kg m-2]
dpns :: dpns [in] Vertical sum of dp0k [H ~> m or kg m-2]
dsns :: dsns [in] Vertical sum of ds0k [H ~> m or kg m-2]
fixlay :: fixlay [out] Deepest fixed coordinate layer
qhrlx :: qhrlx [out] Fractional relaxation within a timestep (between 0 and 1) [nondim]
dp0ij :: dp0ij [out] minimum layer thickness [H ~> m or kg m-2]
dp0cum :: dp0cum [out] minimum interface depth [H ~> m or kg m-2]

Called from:

hybgen_regrid

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function mom_hybgen_regrid/cushn(delp, dp0)

The cushion function from Bleck & Benjamin, 1992, which returns a smoothly varying but limited value that goes between dp0 and delp.

Called from:: hybgen_column_regrid

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subroutine mom_hybgen_regrid/hybgen_column_regrid(CS, nk, thkbot, Rcv_tgt, fixlay, qhrlx, dp0ij, dp0cum, Rcv, h_in, dp_int)

Create a new grid for a column of water using the Hybgen algorithm.

Parameters:

cs :: [in] hybgen regridding control structure
nk :: nk [in] number of layers
thkbot :: thkbot [in] thickness of bottom boundary layer [H ~> m or kg m-2]
rcv_tgt :: [in] Target potential density [R ~> kg m-3]
fixlay :: fixlay [in] deepest fixed coordinate layer
qhrlx :: qhrlx [in] relaxation coefficient per timestep [nondim]
dp0ij :: dp0ij [in] minimum layer thickness [H ~> m or kg m-2]
dp0cum :: dp0cum [in] minimum interface depth [H ~> m or kg m-2]
rcv :: [in] Coordinate potential density [R ~> kg m-3]
h_in :: h_in [in] Layer thicknesses [H ~> m or kg m-2]
dp_int :: dp_int [out] The change in interface positions [H ~> m or kg m-2]

Call to:

cushn mom_error_handler::mom_error

Called from:

hybgen_regrid

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