gridit-cdf v3.2.3¶

Mercurial revision 5770:c90c3015e72d | 2026-05-22

Description¶

gridit-cdf converts unstructured tidal atlases into structured grids. It is designed to process tidal data and generate structured outputs for further analysis or visualization.

Usage¶

gridit-cdf input [OPTIONS] wave1 [wave2 ...]

Options¶

General Options¶

Option	Description
`-h`, `--help`	Display help and exit.

Grid Definition Options¶

Option	Description
`--mapping`	Define grid mapping as `[lonmin:dlon:lonmax; latmin:dlat:latmax].` dlon`and`dlat`are optional. Supported units:`d`(degrees),`m`(minutes),`’`(arcminutes),`s`(seconds),`” `(arcseconds)`.
`-z`	Zone name or global resolution.

Input/Output Options¶

Option	Description
`-c`	NetCDF input atlas file name convention.
`-p`	Directory containing the atlas files. Default: Current directory (`.`).
`-o`	Output root convention. Default: `WAVE.generic`.
`-a`	Frame index to process. Default: `-1` (last frame).
`--ascii`	Use ASCII input format.

Variable and Wave Options¶

Option	Description
`-v`	Up to 6 variable names for amplitudes and phases of `e`, `u`, and `v`. Default: Computed from discretization (as TUGO would).
`-g`	Grid file followed by up to 3 gridded variable names for `e`, `u`, and `v`.
`-discretisation`	Discretization pair for NetCDF input atlas. Used for default variable names if not explicitly provided.
`-`	Separator between variable name list and wave names.

Mesh and Notebook Options¶

Option	Description
`-n`	Notebook file.
`-m`	Mesh file.

Advanced Options¶

Option	Description
`--persistence`	Number of iterations for growth of unmasked pixels.
`--subsampling`	Subsampling factor. Default: `1` (no subsampling).

Examples¶

Basic Conversion with Global Zone¶

Convert tidal atlas for wave M2 using the DNP1xLGP2 discretization:

gridit-cdf -z global -c WAVE.spectral.nc -o WAVE.FES2012 M2 -discretisation DNP1xLGP2

Custom Mapping and Variable¶

Convert tidal atlas with a custom mapping and variable WaveDragRow:

gridit-cdf --mapping [:1m:,:1m:] -c WAVE.spectral.energy.nc -v WaveDragRow -o energy-RG M2

Specify Grid Resolution¶

Convert tidal atlas with a resolution of 0.5 degrees:

gridit-cdf -dx 0.5 -dy 0.5 -c WAVE.spectral.nc -o WAVE.output M2 S2

Use ASCII Input¶

Convert ASCII-formatted tidal atlas:

gridit-cdf --ascii -m mesh_file.nc -c WAVE.ascii -o WAVE.output M2

Process Multiple Waves¶

Convert tidal atlas for multiple waves (M2, S2, K1):

gridit-cdf -z global -c WAVE.spectral.nc -o WAVE.FES2012 M2 S2 K1

Custom Grid Span¶

Convert tidal atlas with a custom grid span:

gridit-cdf -xmin -10 -xmax 10 -ymin -5 -ymax 5 -c WAVE.spectral.nc -o WAVE.output M2

Environment Variables¶

gridit-cdf does not explicitly rely on environment variables for its core functionality. However, if used in a parallelized environment (e.g., with OpenMP), standard environment variables like OMP_NUM_THREADS may influence performance.

Notes¶

Conventions for File Naming:

WAVE is replaced by the uppercase wave name (e.g., M2).
wave is replaced by the lowercase wave name (e.g., m2).
Wave is replaced by the capitalized wave name (e.g., M2).
If the file exists without replacements, no substitution is performed.

Variable Naming:

If -v is not specified, variable names are computed from the discretization.
Up to 6 variables can be specified for amplitudes and phases.

Grid Files:

If -g is used, up to 3 gridded variables can be specified for e, u, and v.

Subsampling:

Use --subsampling to reduce the resolution of the output grid.

Persistence:

--persistence controls the iterative growth of unmasked pixels, useful for filling gaps in the data.