mom_interface_filter module reference¶

Interface height filtering module.

Data Types¶

interface_filter_cs

Control structure for interface height filtering.

Functions/Subroutines¶

`interface_filter()`	Apply a transport that leads to a smoothing of interface height, subject to limits that ensure stability and positive definiteness of layer thicknesses.
`filter_interface()`	Calculates parameterized layer transports for use in the continuity equation.
`interface_filter_init()`	Initialize the interface height filtering module/structure.
`interface_filter_end()`	Deallocate the interface height filtering control structure.

Detailed Description¶

Interface height filtering¶

Interface height filtering is implemented via along-layer mass fluxes

\[h^\dagger \leftarrow h^n - \Delta t \nabla \cdot ( \vec{uh}^* )\]

where the mass fluxes are cast as the difference in vector streamfunction

\[\vec{uh}^* = \delta_k \vec{\psi} .\]

The streamfunction is proportional to the slope in the difference between unsmoothed interface heights and those smoothed with one (or more) passes of a Laplacian filter, depending on the order of the filter, or to the slope for a Laplacian filter

\[\vec{\psi} = - \kappa_h {\nabla \eta - \eta_smooth}\]

The result of the above expression is subsequently bounded by minimum and maximum values, including a maximum smoothing rate for numerical stability ( \(\kappa_{h}\) is calculated internally).

Module mom_interface_filter parameters¶

Symbol	Module parameter
	`APPLY_INTERFACE_FILTER`
	`INTERFACE_FILTER_TIME`
	`INTERFACE_FILTER_MAX_CFL`
	`INTERFACE_FILTER_ORDER`

Type Documentation¶

type mom_interface_filter/interface_filter_cs¶

Control structure for interface height filtering.

Type fields:

% id_uh_sm [integer] :: Diagnostic identifier.
% id_vh_sm [integer] :: Diagnostic identifier.
% id_l2_u [integer] :: Diagnostic identifier.
% id_l2_v [integer] :: Diagnostic identifier.
% id_sfn_x [integer] :: Diagnostic identifier.
% id_sfn_y [integer] :: Diagnostic identifier.
% initialized [logical] :: True if this control structure has been initialized.
% max_smoothing_cfl [real] :: Maximum value of the smoothing CFL for interface height filtering [nondim].
% filter_rate [real] :: The rate at which grid-scale anomalies are damped away [T-1 ~> s-1].
% filter_order [integer] :: The even power of the interface height smoothing. At present valid values are 0, 2, or 4.
% interface_filter [logical] :: If true, interfaces heights are diffused.
% isotropic_filter [logical] :: If true, use the same filtering lengthscales in both directions, otherwise use filtering lengthscales in each direction that scale with the grid spacing in that direction.
% debug [logical] :: write verbose checksums for debugging purposes
% diag [type( diag_ctrl ),pointer] :: structure used to regulate timing of diagnostics

Function/Subroutine Documentation¶

subroutine mom_interface_filter/interface_filter(h, uhtr, vhtr, tv, dt, G, GV, US, CDp, CS)¶

Apply a transport that leads to a smoothing of interface height, subject to limits that ensure stability and positive definiteness of layer thicknesses. It also updates the along-layer mass fluxes used in the tracer transport equations.

Parameters:

g :: [in] Ocean grid structure
gv :: [in] Vertical grid structure
us :: [in] A dimensional unit scaling type
h :: [inout] Layer thickness [H ~> m or kg m-2]
uhtr :: [inout] Accumulated zonal mass flux [L2 H ~> m3 or kg]
vhtr :: [inout] Accumulated meridional mass flux [L2 H ~> m3 or kg]
tv :: [in] Thermodynamics structure
dt :: [in] Time increment [T ~> s]
cdp :: [inout] Diagnostics for the continuity equation
cs :: [inout] Control structure for interface height filtering

Call to:

filter_interface mom_error_handler::mom_error

subroutine mom_interface_filter/filter_interface(h, e, Lsm2_u, Lsm2_v, uhD, vhD, tv, G, GV, US, halo_size)¶

Calculates parameterized layer transports for use in the continuity equation. Fluxes are limited to give positive definite thicknesses. Called by interface_filter(). .

Parameters:

g :: [in] Ocean grid structure
gv :: [in] Vertical grid structure
us :: [in] A dimensional unit scaling type
h :: [in] Layer thickness [H ~> m or kg m-2]
e :: [in] Interface positions [Z ~> m]
lsm2_u :: [in] Interface smoothing lengths squared at u points [L2 ~> m2]
lsm2_v :: [in] Interface smoothing lengths squared at v points [L2 ~> m2]
uhd :: [out] Zonal mass fluxes [H L2 ~> m3 or kg]
vhd :: [out] Meridional mass fluxes [H L2 ~> m3 or kg]
tv :: [in] Thermodynamics structure
halo_size :: [in] The size of the halo to work on, 0 by default.

Called from:

interface_filter

subroutine mom_interface_filter/interface_filter_init(Time, G, GV, US, param_file, diag, CDp, CS)¶

Initialize the interface height filtering module/structure.

Parameters:

time :: [in] Current model time
g :: [in] Ocean grid structure
gv :: [in] Vertical grid structure
us :: [in] A dimensional unit scaling type
param_file :: [in] Parameter file handles
diag :: [inout] Diagnostics control structure
cdp :: [inout] Continuity equation diagnostics
cs :: [inout] Control structure for interface height filtering

Call to:

mom_error_handler::mom_error mom_diag_mediator::register_diag_field

subroutine mom_interface_filter/interface_filter_end(CS, CDp)¶

Deallocate the interface height filtering control structure.

Parameters:

cs :: [inout] Control structure for interface height filtering
cdp :: [inout] Continuity diagnostic control structure