comodo-filter v3.2.3¶

Mercurial revision 5770:c90c3015e72d | 2026-05-22

Description¶

comodo-filter filters comodo-compliant NetCDF files at a given frequency and produces energy atlases. It performs DF-II IIR filtering on the input files and generates:

Filtered output data.
Energy atlases (if enabled).

Usage¶

comodo-filter file1 [file2 ...] [OPTIONS]

Options¶

General Options¶

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

Input/Output Options¶

Option	Description
`-l <file>`	Path to a file containing a list of input files (overrides command-line file list).
`-g <file>`	Path to the grid file.
`-p <prefix>`	Output prefix (can be a folder path followed by `/`). Recommended: Use a different hard drive for filtering to improve performance.
`--output <path>`	Output path for results.
`--path <path>`	Path to input data.
`--mesh <file>`	Path to the mesh file (for unstructured grids).

Filtering Options¶

Option	Description
`-v <var1> [var2 ...]`	List of variables to filter.
`-w <frequency>`	Frequency at which to filter (in deg/h).
`-q <value>`	Q factor for filtering.
`--cut-off <frequency>`	Cut-off frequency for filtering.
`--frequencies <f1> [f2 ...]`	List of frequencies to filter (space-separated).
`--half-window <value>`	Half-window size for filtering (default: `3.0`).
`--sampling <value>`	Sampling rate for unstructured grids.

Atlas Options¶

Option	Description
`-a`	Produce energy atlases.
`--only-atlases`	Produce only atlases (no filtered output data).
`-c <convention>`	Convention for input files. Currently without effect.

Control and Grid Options¶

Option	Description
`--control <file>`	Path to a file containing control points (ASCII format: number of points followed by `longitude latitude [layer]`).
`--unstructured`	Use unstructured grid mode.

Date Options¶

Option	Description
`-s <date>`	Start date in `dd/mm/yyyy` format.
`-f <date>`	End date in `dd/mm/yyyy` format.
`--time-origin <date>`	Default date origin in `dd/mm/yyyy` format.

Miscellaneous Options¶

Option	Description
`--persistence <value>`	Persistence value for filtering.
`--convention <name>`	Convention name for input files.

Examples¶

Basic Filtering¶

Filter variables ssh and tem at frequency M2:

comodo-filter -v ssh tem -w M2 -p output/ file1.nc file2.nc

Filtering with Q Factor¶

Filter variable ssh at frequency M2 with a Q factor of 10:

comodo-filter -v ssh -w M2 -q 10 -p output/ file1.nc

Filtering with Cut-Off Frequency¶

Filter variable ssh with a cut-off frequency of 5 deg/h:

comodo-filter -v ssh --cut-off 5 -p output/ file1.nc

Filtering Multiple Frequencies¶

Filter variable ssh for frequencies M2 and S2:

comodo-filter -v ssh --frequencies M2 S2 -p output/ file1.nc

Generate Energy Atlases Only¶

Generate atlases without outputting filtered data:

comodo-filter -v ssh -w M2 --only-atlases -p output/ file1.nc

Filtering with Control Points¶

Filter variable ssh at frequency M2 using control points:

comodo-filter -v ssh -w M2 --control control.dat -p output/ file1.nc

Unstructured Grid Filtering¶

Filter variable ssh for unstructured grids:

comodo-filter -v ssh --unstructured --mesh mesh.nc --path input/ -p output/

Filtering with Date Range¶

Filter variable ssh between 01/01/2020 and 31/12/2020:

comodo-filter -v ssh -s 01/01/2020 -f 31/12/2020 -p output/ file1.nc

Environment Variables¶

comodo-filter uses OpenMP (version 201511) for parallelization. Key environment variables:

Variable	Description
`OMP_NUM_THREADS`	Number of threads to use.
`OMP_SCHEDULE`	Runtime schedule type and chunk size.
`OMP_DYNAMIC`	Enable/disable dynamic thread adjustment.
`OMP_NESTED`	Enable/disable nested parallelism.

Example:

OMP_NUM_THREADS=6 comodo-filter -v ssh -w M2 -p output/ file1.nc

Note: If running on a busy machine, limit threads to the number of free CPUs to avoid performance degradation.

Notes¶

Input Files:

Must be comodo-compliant NetCDF files.
The time variable must follow CF conventions (if applicable).

Output:

Filtered files are saved with the specified output prefix (-p).
Atlases are generated if -a or --only-atlases is used.

Performance:

For large datasets, use -p to output to a different hard drive to avoid I/O bottlenecks.
Adjust OMP_NUM_THREADS based on available CPU resources.

Bug:

When specifying more than one variable, atlases are not produced. This is a known issue.

Unstructured Grids:

Use --unstructured for unstructured grid data. Requires --mesh and --path options.