Tutorial

The distribution contains a time series fes_tide_time_series.nc that will be used in this help. This file is located in the tests/dataset directory at the root of the project.

The first step is to read this time series using the NetCDF4 library, for example:

import netCDF4
import pytide

with netCDF4.Dataset("tests/dataset/fes_tide_time_series.nc") as dataset:
    time = (ds.variables['time'][:]).astype("datetime64[us]")
    h = dataset['ocean'][:] * 1e-2      # cm to m

Then, we will create an instance of a pytide.WaveTable object:

wt = pytide.WaveTable()

By default, all components known by this object are loaded into memory. The list of components known by this object can be retrieved using the pytide.WaveTable.known_constituents() method.

If you want to restrict the analysis to only a few components, you must provide a list to the constructor in order to specify the waves to be analyzed.

wt = pytide.WaveTable(["M2", "K1", "O1", "P1", "Q1", "S1"])

The pytide.WaveTable.constituents() method allows to retrieve the list of waves defined during the construction of the object.

The different nodal corrections are then calculated from the time series to be analyzed:

f, vu = wt.compute_nodal_modulations(time)

These coefficients are used by harmonic analysis to determine the properties of the different tidal waves defined during the construction of the instance.

w = wt.harmonic_analysis(h, f, vu)

This result can then be used to determine a tidal height for the analyzed time series:

hp = wt.tide_from_tide_series(time, w)