showarg v3.2.3¶

Mercurial revision 5786:5c8b45563631 | 2026-08-04

Description¶

showarg displays information about a list of tidal waves or a spectrum name (Wave Lists and Spectra). It provides the following details for each wave:

Astronomic potential (in cm)
Pulsation (in degrees/hour and per hour)
Period (in hours and days)
Critical latitude (in degrees)
Doodson number
Schureman notation

If no list of waves is provided, it displays information for all coded waves, sorted by increasing pulsation, but without wave separations.

Note: Wave names follow the Darwin convention, as described in Schureman (1940, Table 2, pp. 164-167). The Doodson number is also shown. A full list of waves with their Doodson numbers is available from the IHO.

Usage¶

showarg [OPTIONS] [sprectra] [wave1 wave2 ...]

Options¶

Option	Description
`-h`, `--help`	Display help and exit.
`--astronomic`	Specify the astronomic angle convention: `linearSchureman`, `Meeus`, `AVISO-FES-2.9.5`, or `AVISO_SOLID_TIDES`.
`--alias <frequency>`	Specify an aliasing frequency (in days). Not compatible with `--combinations`.
`--combinations`	Show non-linear combinations of all astronomic waves. Not compatible with `--alias`. Ignored if a list of waves is provided.
`--full-accuracy`	Enable maximum number of digits for output precision.
`-s <date>`	Start date in `dd/mm/yyyy` format.
`-f <date>`	End date in `dd/mm/yyyy` format.
`-a`	Show astronomic arguments periodically (default: daily). See `-i` for frequency.
`-i <frequency>`	Specify the daily frequency for displaying arguments (minimum: daily). Implies `-a`.

Wave Lists and Spectra¶

You can specify:

Individual waves (e.g., M2, S2, O1, K1). Run showarg without arguments to see the full list of available waves.
Predefined spectra:
- 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¶

Display Information for Specific Waves¶

Show details for waves M2, S2, O1, and K1:

showarg M2 S2 O1 K1

Display All Coded Waves¶

List all available waves with their properties:

showarg

Use Aliasing Frequency¶

Show waves with an aliasing frequency of 9.9156 days (e.g., for TPJason TPN):

showarg --alias 9.9156

Show waves with an aliasing frequency of 0.99349 days (e.g., for SWOT CalVal orbits):

showarg --alias 0.99349

Show waves with an aliasing frequency of 20.86455 days:

showarg --alias 20.86455

Show Non-Linear Combinations¶

Display non-linear combinations of all astronomic waves:

showarg --combinations

Display Arguments for a Date Range¶

Show astronomic arguments daily from 01/01/2020 to 31/12/2020:

showarg -s 01/01/2020 -f 31/12/2020 -a

Show astronomic arguments every 6 hours for the same period:

showarg -s 01/01/2020 -f 31/12/2020 -a -i 4

Use a Predefined Spectrum¶

Display waves from the COMODO spectrum:

showarg --spectrum COMODO

High-Precision Output¶

Enable maximum precision for wave properties:

showarg --full-accuracy M2 S2

Environment Variables¶

showarg does not use environment variables for its core functionality. However, it relies on standard system libraries for date and time handling.

Notes¶

Wave Naming Convention: All wave names follow the Darwin convention as referenced in Schureman (1940).
Doodson Numbers: The Doodson number is a unique identifier for each tidal constituent, based on its astronomical origins.
Schureman Notation: Provides a detailed breakdown of the wave’s astronomical components (e.g., degree=2: T=2 s=-2 h=2 p=0 p1=0).
Aliasing: Use --alias to simulate the effect of aliasing for specific missions (e.g., satellite orbits).
Combinations: The --combinations option is useful for studying non-linear interactions between waves.
Output Format: By default, separations are shown only if a list of waves is provided. For all waves, separations are omitted.