comodo-detidor v3.2.3¶

Mercurial revision 5770:c90c3015e72d | 2026-05-22

Description¶

comodo-detidor is a tool designed to detide comodo-compliant NetCDF outputs and produce tidal atlases. It is used by CTOH (Centre de Topographie des Océans et de l’Hydrosphère).

The tool performs spectral analysis on a given list of tidal waves and generates:

Detided output files.
Tidal atlases (amplitude and phase maps for each tidal constituent).

Note: The time variable in input files must comply with the CF conventions.

Usage¶

comodo-detidor file1 [file2 ...] [OPTIONS] -d wave1 [wave2 ...]

Options¶

General Options¶

Option	Description
`--help`, `-h`	Display help and exit.
`--nodal=no`	Disable nodal corrections.
`--time-variable <name>`	Alternative name for the time variable (default: `time`).
`--time-attributes <attrs>`	Alternative time attributes (e.g., `"seconds since YYYY/MM/DD"` or `"days since YYYY/MM/DD HH:MM:SS"`).

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 (required if coordinates are missing in input files and atlases/control points are used).
`-p <dir>`	Output directory. Recommended: Use a different hard drive for detiding to improve performance.
`-v <var1> [var2 ...]`	List of variables to detide (e.g., `ssh`, `tem`, `sal`, `XE`).
`-d <wave1> [wave2 ...]`	List of tidal waves to analyze. See Wave list and Spectra.
`--spectrum <name>`	Specifies the detiding spectrum by name. See Wave list and Spectra.

Atlas Options¶

Option	Description
`-a`	Produce tidal atlases.
`--only-atlases`	Produce only atlases (no detiding). Implies `-a`.
`--load-atlases`	Load existing atlases (no analysis). Currently disables `--control`.
`-1`	Store all atlases in one file per variable. ⚠️ Warning: Files produced with this option cannot be used with `comodo-admittance`.

Analysis Options¶

Option	Description
`-c <file>`, `--control <file>`	Path to a file containing control points (ASCII format: number of points followed by `longitude latitude [layer]`).
`--drying`	Account for slight variations in the mask at each time frame. Useful for cases with dynamically changing land-sea masks.
`--take-first`	If time frames are simultaneous, use the first one.
`--take-last`	If time frames are simultaneous, use the last one.
`--band-cut <f1> <f2>`	Band-cut filter: specify two frequencies (in deg/h) to exclude waves outside this range.
`--averaging <time>`	Deprecated. Use `--averaging-interval` instead.
`--averaging-interval <[min:max]>`	Time integration range (in seconds) for time-averaged data (e.g., `"[-3600:0]"` for hourly averages).
`--altimetry`	Special mode for altimetry data. Implies `--load-atlases -v elevation`. Do not prepend `detided_` to output variable names. Also copies `Pa` and mesh variables without detiding.

Date Options¶

Option	Description
`-s <date>`	Start date for analysis. See Date Formats.
`-f <date>`	End date for analysis. See Date Formats.
`-o <date>`	Default date origin. See Date Formats.

Miscellaneous Options¶

Option	Description
`-t`	Display separation tables for all harmonics and list of files within time boundaries.

Date Formats¶

Supported formats:

yyyy/mm/dd HH:MM:SS.SSS
dd/mm/yyyy HH:MM:SS.SSS
mm/yyyy

Notes:

The least significant parts (seconds, minutes, hours, days, months) are optional.

The separator can be any non-numeric character (e.g., /, -, `` ).

End dates are inclusive. Examples:

2000 → 2001/01/01 00:00:00

2000/01 → 2000/02/01 00:00:00

2000/01/01 → 2000/01/02 00:00:00

2000/01/01 00 → 2000/01/01 01:00:00

2000/01/01 00:00 → 2000/01/01 00:01:00

Wave Lists and Spectra¶

You can specify:

Individual waves (run showarg to see the full list of available waves):

A good start is Q1 O1 P1 K1 N2 M2 S2 K2 M4 MS4.

Predefined spectra (see showarg to get associated waves and the duration needed for wave separation):

ESTUARINE
ESTUARINE-HF
COMODO
COASTAL
COASTAL-HF
SHELF
SHELF-HF
DEEP
DEEP-HF
REDUCED
CURRENTS-HF
FES2022c
AVISO-FES-SP
AVISO-FES-ADMITTANCE
AVISO-FES-LP
AVISO-FES-LP-PROXY

Examples¶

Basic Detiding¶

Detide variables ssh, tem, and sal for waves M2, S2, N2, K2:

comodo-detidor -s 15/12/2008 -f 28/02/2009 \
  -l files.list -control control.dat \
  -g grille_domconcat.nc \
  -v ssh tem sal \
  -a -d M2 S2 N2 K2

Detiding with Custom Waves¶

Detide variable XE for a custom set of waves:

comodo-detidor -s 02/01/2000 \
  -control control.dat \
  -v XE \
  -a \
  -d K1 O1 Q1 M2 S2 N2 K2 L2 2N2 2NS2 2SM2 2SN2 MK3 M4 SN4 MS4 3MS4 MN4 S4 M6 2MS6

Only Generate Atlases¶

Generate atlases without detiding:

comodo-detidor -l files.list \
  -g grille_domconcat.nc \
  -v ssh \
  --only-atlases \
  -d M2 S2 N2 K2

Load Existing Atlases¶

Load precomputed atlases for detiding:

comodo-detidor -l files.list \
  --load-atlases \
  -v elevation \
  -d M2 S2

Altimetry Mode¶

Process altimetry data (implies --load-atlases -v elevation):

comodo-detidor -l files.list \
  --altimetry \
  -d M2 S2 K1

Band-Cut Filtering¶

Exclude waves outside the frequency range [5, 20] deg/h:

comodo-detidor -l files.list \
  -v ssh \
  --band-cut 5 20 \
  -d M2 S2 K1 O1

Time Averaging¶

Specify a time-averaging interval of [-3600:0] (1 hour backward):

comodo-detidor -l files.list \
  -v ssh \
  --averaging-interval "[-3600:0]" \
  -d M2 S2

Using a Predefined Spectrum¶

Use the COMODO spectrum:

comodo-detidor -l files.list \
  -v ssh \
  -a \
  -d COMODO

Environment Variables¶

comodo-detidor 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-detidor -l files.list -v ssh -d M2 S2

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.

Output:

Detided files are saved in the specified output directory (-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.

Mask Handling:

Use --drying for cases where the land-sea mask varies slightly between frames.
For more complex masking (e.g., many points masked), consider using adcp instead.

Simultaneous Frames:

Use --take-first or --take-last to handle simultaneous time frames.