# mom_geothermal module reference¶

Implemented geothermal heating at the ocean bottom.

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## Data Types¶

 geothermal_cs Control structure for geothermal heating.

## Functions/Subroutines¶

 geothermal_entraining() Applies geothermal heating, including the movement of water between isopycnal layers to match the target densities. geothermal_in_place() Applies geothermal heating to the bottommost layers that occur within GEOTHERMAL_THICKNESS of the bottom, by simply heating the water in place. geothermal_init() Initialize parameters and allocate memory associated with the geothermal heating module. geothermal_end() Clean up and deallocate memory associated with the geothermal heating module.

## Detailed Description¶

Geothermal heating can be added either in a layered isopycnal mode, in which the heating raises the density of the layer to the target density of the layer above, and then moves the water into that layer, or in a simple Eulerian mode, in which the bottommost GEOTHERMAL_THICKNESS are heated. Geothermal heating will also provide a buoyant source of bottom TKE that can be used to further mix the near-bottom water. In cold fresh water lakes where heating increases density, water should be moved into deeper layers, but this is not implemented yet.

## Type Documentation¶

type mom_geothermal/geothermal_cs

Control structure for geothermal heating.

Type fields
• % drcv_dt_inplace [real] :: The value of dRcv_dT above which (dRcv_dT is negative) the water is heated in place instead of moving upward between layers in non-ALE layered mode [R degC-1 ~> kg m-3 degC-1].

• % geo_heat [real(:,:),allocatable] :: The geothermal heat flux [J m-2 T-1 ~> W m-2].

• % geothermal_thick [real] :: The thickness over which geothermal heating is applied [H ~> m or kg m-2].

• % apply_geothermal [logical] :: If true, geothermal heating will be applied. This is false if GEOTHERMAL_SCALE is 0 and there is no heat to apply.

• % time [type(time_type),pointer] :: A pointer to the ocean model’s clock.

• % diag [type(diag_ctrl),pointer] :: A structure that is used to regulate the timing timing of diagnostic output.

• % id_internal_heat_heat_tendency [integer] :: ID for diagnostic of heat tendency.

• % id_internal_heat_temp_tendency [integer] :: ID for diagnostic of temperature tendency.

• % id_internal_heat_h_tendency [integer] :: ID for diagnostic of thickness tendency.

## Function/Subroutine Documentation¶

subroutine mom_geothermal/geothermal_entraining(h, tv, dt, ea, eb, G, GV, US, CS, halo)

Applies geothermal heating, including the movement of water between isopycnal layers to match the target densities. The heating is applied to the bottommost layers that occur within GEOTHERMAL_THICKNESS of the bottom. If the partial derivative of the coordinate density with temperature is positive or very small, the layers are simply heated in place. Any heat that can not be applied to the ocean is returned (WHERE)?

Parameters
• g :: [inout] The ocean’s grid structure.

• gv :: [in] The ocean’s vertical grid structure.

• h :: [inout] Layer thicknesses [H ~> m or kg m-2]

• tv :: [inout] A structure containing pointers to any available thermodynamic fields.

• dt :: [in] Time increment [T ~> s].

• ea :: [inout] The amount of fluid moved downward into a layer; this should be increased due to mixed layer detrainment [H ~> m or kg m-2]

• eb :: [inout] The amount of fluid moved upward into a layer; this should be increased due to mixed layer entrainment [H ~> m or kg m-2].

• us :: [in] A dimensional unit scaling type

• cs :: The control structure returned by a previous call to geothermal_init.

• halo :: [in] Halo width over which to work

Call to

mom_error_handler::mom_error

subroutine mom_geothermal/geothermal_in_place(h, tv, dt, G, GV, US, CS, halo)

Applies geothermal heating to the bottommost layers that occur within GEOTHERMAL_THICKNESS of the bottom, by simply heating the water in place. Any heat that can not be applied to the ocean is returned (WHERE)?

Parameters
• g :: [inout] The ocean’s grid structure.

• gv :: [in] The ocean’s vertical grid structure.

• h :: [in] Layer thicknesses [H ~> m or kg m-2]

• tv :: [inout] A structure containing pointers to any available thermodynamic fields.

• dt :: [in] Time increment [T ~> s].

• us :: [in] A dimensional unit scaling type

• cs :: The control structure returned by a previous call to geothermal_init.

• halo :: [in] Halo width over which to work

Call to

mom_error_handler::mom_error

subroutine mom_geothermal/geothermal_init(Time, G, GV, US, param_file, diag, CS, useALEalgorithm)

Initialize parameters and allocate memory associated with the geothermal heating module.

Parameters
• time :: [in] Current model time.

• g :: [inout] The ocean’s grid structure.

• gv :: [in] The ocean’s vertical grid structure.

• us :: [in] A dimensional unit scaling type

• param_file :: [in] A structure to parse for run-time parameters.

• diag :: [inout] Structure used to regulate diagnostic output.

• cs :: Pointer pointing to the module control structure.

• usealealgorithm :: [in] logical for whether to use ALE remapping

Call to
Called from

mom_diabatic_driver::diabatic_driver_init

subroutine mom_geothermal/geothermal_end(CS)

Clean up and deallocate memory associated with the geothermal heating module.

Parameters

cs :: [inout] Geothermal heating control structure that will be deallocated in this subroutine.

Called from

mom_diabatic_driver::diabatic_driver_end