# tracers3D Section

This section configures **3D tracer simulations**, including **vertical discretization** and **diffusion**.

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 | **Parameter** | **Description** |
 |---------------|----------------|
 | `3D_computation` | Flag to enable/disable 3D tracer computations (`TRUE`, `FALSE`). |
 | `Tracers_integration` | Time integration scheme for tracers (`FORWARD`, `LEAPFROG`, `EULER-BF`). |
 | `tracers_mode` | Mode for tracers (`STATIC`, `DIAGNOSTIC`, `PROGNOSTIC`). |
 | `tracers_discretisation` | Discretization for tracers (`LGP0`, `LGP1`, `QLP1`). |
 | `tracers_vertical_discretisation` | Vertical discretization for tracers (`LGP0`, `LGP1`, `DGP1`). |
 | `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`, `UNIFORM-N`, `PROFILE`, `UG-ARCHIVE`, `SG-ARCHIVE`). |
 | `initialisation_files_directory` | Directory for initialization files. |
 | `temperature_initialisation_file` | File for temperature initialization. |
 | `temperature_variable` | Name of temperature variable (default: `AUTO`). |
 | `salinity_initialisation_file` | File for salinity initialization. |
 | `salinity_variable` | Name of salinity variable (default: `AUTO`). |
 | `density_initialisation_file` | File for density initialization. |
 | `density_variable` | Name of density variable (default: `AUTO`). |
 | `tracer_profile_file` | File for tracer profile initialization. |
 | `tracers_initialisation` | Initialization method for tracers (`VARIATIONAL`, `INTERPOLATION`). |
 | `turbulence_closure` | Turbulence closure model (`CONSTANT`, `YAMADA`, `GALPERIN`, `GASPAR`, `TKE`, `KOMEGA`, `HOMOGENEOUS`). |
 | `tracers_lateral_diffusion_coefficient` | Lateral diffusion coefficient for tracers (default: `0.0 m²/s`). |
 | `tracers_horizontal_diffusion_coefficient` | Horizontal diffusion coefficient for tracers (default: `0.0 m²/s`). |
 | `tracer_vertical_diffusion_coefficient` | Vertical diffusion coefficient for tracers (default: `1.e-04 m²/s`). |
 | `tracers_Hsmoothing` | Flag to enable/disable horizontal smoothing for tracers (`TRUE`, `FALSE`). |
 | `compute_diagnostics` | Flag to compute diagnostics for tracers (`TRUE`, `FALSE`). |