DIWASP - DIrectional WAve SPectra Toolbox#

Python Port - Version 0.1.0

A Python package for estimating directional wave spectra from multi-sensor measurements. This is a port of the original DIWASP Matlab toolbox developed by David Johnson at the Coastal Oceanography Group, Centre for Water Research, University of Western Australia.

Overview#

DIWASP is a toolbox for the estimation of directional wave spectra. Spectra can be calculated from a variety of data types using a single function dirspec. Five different estimation methods are available depending on the quality or speed of estimation required. Utility functions are also included to manage spectra, plot results, and run tests on the estimation methods.

Features#

  • Multiple estimation methods: DFTM, EMLM, IMLM, EMEP, BDM

  • Flexible sensor support: Pressure, velocity, elevation, acceleration, slope, and displacement sensors

  • xarray/wavespectra integration: Output compatible with the wavespectra package

  • Synthetic spectrum generation: Create test spectra and sensor data

Supported Data Types#

All standard wave recorder data types are supported:

  • Surface elevation (elev)

  • Pressure (pres)

  • Current velocity components (velx, vely, velz)

  • Surface slope components (slpx, slpy)

  • Water surface vertical velocity (vels)

  • Water surface vertical acceleration (accs)

  • Current accelerations (accx, accy, accz)

  • Horizontal displacement (dspx, dspy)

Estimation Methods#

Five different estimation methods can be used, each with different levels of performance in terms of accuracy, speed, and suitability for different data types:

Method

Name

Reference

DFTM

Direct Fourier Transform Method

Barber (1961)

EMLM

Extended Maximum Likelihood Method

Isobe et al. (1984)

IMLM

Iterated Maximum Likelihood Method

Pawka (1983)

EMEP

Extended Maximum Entropy Principle

Hashimoto et al. (1993)

BDM

Bayesian Direct Method

Hashimoto and Kobune (1987)

Quick Start#

from diwasp import dirspec, InstrumentData, SensorType, EstimationParameters
import numpy as np

# Load or create sensor data
data = np.loadtxt('wave_data.csv')  # [n_samples x n_sensors]

# Define sensor configuration
instrument = InstrumentData(
    data=data,
    layout=np.array([[0, 10, 0], [0, 0, 10], [10, 10, 10]]).T,
    datatypes=[SensorType.PRES, SensorType.VELX, SensorType.VELY],
    depth=20.0,
    fs=2.0
)

# Estimate spectrum
spectrum, info = dirspec(instrument)

print(f"Hsig: {info.hsig:.2f} m")
print(f"Peak period: {info.tp:.2f} s")
print(f"Peak direction: {info.dp:.1f} deg")

License#

DIWASP is free software distributed under the MIT License. See LICENSE for details.

Citation#

This document should be referenced as:

Johnson, D. (2002) “DIWASP, a directional wave spectra toolbox for MATLAB: User Manual.” Research Report WP-1601-DJ (V1.1), Centre for Water Research, University of Western Australia.

Documentation Contents#