Conventions

Wavespectra takes advantage of xarray’s labelled coordinates to abstract n-dimensional wave spectra datasets. This requires some conventions around special coordinates and variables. The convention adopted is based on that of the netcdf output from the WAVEWATCH III spectral wave model.

Coordinates

Wave frequency

Wave frequency coordinate with name freq, defined in \(Hz\) (required).

Wave direction

Wave direction coordinate in coming-from convention, with name dir, defined in \(degree\) (required for 2D spectra and directional methods).

Time

Time coordinate with name time (required by a few methods).

Data variables

Wave energy density

Wave energy density array named with name efth, defined in:

• 2D spectra \(E(\sigma,\theta)\): \(m^{2}{degree^{-1}}{s}\).

• 1D spectra \(E(\sigma)\): \(m^{2}{s}\).

Wind speed

Wind speed array named with name wspd, defined in \(ms^{-1}\) (required for the watershed partitioning).

Wind direction

Wind direction array with wdir, defined in \(degree\) (required for the watershed partitioning).

Water depth

Water depth array with name dpt, defined in \(m\) (required for the watershed partitioning and wavenumber-based methods).

Attributes

Pre-defined names and units for these and other coordinates and variables are provided in the wavespectra.core.attributes module:

In [1]: from wavespectra.core.attributes import attrs

In [2]: attrs.SPECNAME
Out[2]: 'efth'

In [3]: attrs.ATTRS.hs
Out[3]: 
{'standard_name': 'sea_surface_wave_significant_height',
 'units': 'm',
 '_ipython_canary_method_should_not_exist_': {}}