# 3D Section

This section configures the **3D model settings** in T-UGOm. It includes parameters for **vertical discretization**, **time integration**, **tracer modes**, and **turbulence closure** for 3D simulations.

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 | **Parameter** | **Description** |
 |---------------|----------------|
 | `3D_computation` | Flag to enable/disable 3D computations (`TRUE`, `FALSE`). |
 | `3D_time_step` | Time step for 3D simulations (default: `$2D_time_step`, in seconds). |
 | `Momentum_integration` | Time integration scheme for momentum (`FORWARD`, `LEAPFROG`, `EULER-BF`). |
 | `Tracers_integration` | Time integration scheme for tracers (`FORWARD`, `LEAPFROG`, `EULER-BF`). |
 | `3D_mode` | Mode for 3D computations (`BAROCLINIC`, `BAROTROPIC`). |
 | `tracers_mode` | Mode for tracers (`STATIC`, `DIAGNOSTIC`, `PROGNOSTIC`). |
 | `pressure_mode` | Pressure mode (`HYDROSTATIC`, `NON-HYDROSTATIC`). |
 | `w_derivation` | Method for deriving vertical velocity (`DIRECT`, `WE-CONSISTENT`). |
 | `w_discretisation` | Vertical velocity discretization: Hori x Vert (`LGP0xLGP1`, `LGP1xLGP1`). |
 | `p_horizontal_discretisation` | Horizontal discretization for pressure (`LGP0`, `LGP1`). |
 | `p_vertical_discretisation` | Vertical discretization for pressure (`LGP0`, `LGP1`). |
 | `tracers_discretisation` | Discretization for tracers (`LGP0`, `LGP1`, `QLP1`). |
 | `tracers_vertical_resolution` | Vertical resolution for tracers (default: `1`, in layers). |
 | `tracers_advection_centering` | Advection centering for tracers (default: `0.5`, dimensionless). |
 | `tracer_initialisation` | Initialization method for tracers (`HOMOGENEOUS`, `PROFILE`, `MODEL`). |
 | `initialisation_files_directory` | Directory for initialization files. |
 | `temperature_initialisation_file` | File for temperature initialization. |
 | `salinity_initialisation_file` | File for salinity initialization. |
 | `density_initialisation_file` | File for density initialization. |
 | `tracer_profile_file` | File for tracer profile initialization. |
 | `max_number_layers` | Maximum number of vertical layers (default: `20`). |
 | `number_of_upper_horizontal_layers` | Number of upper horizontal layers (default: `0`). |
 | `limit_of_upper_horizontal_layers` | Depth limit for upper horizontal layers (default: `-50 m`). |
 | `level_distribution` | Distribution of vertical levels (`COSINUS`, `BOTTOM-COSINUS`, `SURFACE-COSINUS`, `UNIFORM`, `COMODO`, `FILE`). |
 | `level_optimisation` | Optimization method for vertical levels (`NONE`, `DENSITY-LAPLACIAN`, `MODAL`, `ISOPYCNAL`). |
 | `level_displacement` | Displacement mode for vertical levels (`SURFACE-ONLY`, `ALL`, `RIGID-LID`). |
 | `turbulence_closure` | Turbulence closure model (`CONSTANT`, `YAMADA`, `GALPERIN`, `GASPAR`, `TKE`, `KOMEGA`, `HOMOGENEOUS`). |
 | `lateral_diffusion_coefficient` | Lateral diffusion coefficient (default: `0.0 m²/s`). |
 | `vertical_diffusion_coefficient` | Vertical diffusion coefficient (default: `1.e-04 m²/s`). |
 | `tracer_vertical_diffusion_coefficient` | Vertical diffusion coefficient for tracers (default: `1.e-04 m²/s`). |



 ## Deprecated options
 
 | **Parameter** | **Description** | **Coment** |
 |---------------|-----------------|------------|
 | `v_discretisation` | Horizontal velocity discretization (`LGP0`, `LGP1`, `NCP1`). | Now replace by [2D discretization](2D.md) but only these 3 options are available sur 3D runs. |
 | `v_vertical_discretisation` | Vertical velocity discretization (`LGP0`). | Now forced to be `LGP0`. |
 | `tracers_vertical_discretisation` | Vertical discretization for tracers (`LGP0`, `LGP1`). | Now controled by `tracers_discretisation`: if `LGP0` or `LGP1`, then the vertical discretisation will be `LGP0`; if `QLP1`, then the vertical discretisation will be `LGP1` |