SFY -- A lightweight, high-frequency and phase-resolving wave-buoy for coastal waters

TL;DR

This paper introduces SFY, a lightweight, high-frequency wave buoy designed for coastal waters, capable of detailed wave analysis and data transmission via cellular networks, enabling improved wave and current interaction studies.

Contribution

The paper presents a novel low-cost, high-frequency, phase-resolving wave buoy with cellular data transmission, tested in various conditions, enhancing wave measurement accuracy near coastlines.

Findings

Successfully measured and quantified breaking waves in open water.

Achieved higher accuracy in wave trajectory recovery than previous methods.

Identified and addressed low-frequency noise issues in IMU-based measurements.

Abstract

Small lightweight wave buoys, SFYs, designed to operate near the coast, have been developed. The buoys are designed to record and transmit the full time series of surface acceleration at $52$ Hz. The buoy uses the cellular network to transfer data and position (up to $80$ km from the base station). This reduces costs and increases band-width. The low cost and low weight permits the buoys to be deployed easily, and in arrays in areas where satellite and wave models struggle to resolve wave and current interaction. The buoys are tested in a wave-flume, the open water and in the breaking waves of the surf. The conditions range from calm to significant wave heights exceeding $7$ m and crashing breakers with accelerations exceeding $10$ g. The high sample rate captures the impulse of breaking waves, and allows them to be studied in detail. Breaking waves are measured and quantified in the open water. We measure breaking waves in the surf and recover the trajectory of waves breaking in the field to a higher degree than previously done. The time series of surface elevation, and accurate positioning, permits the signal of adjacent buoys to be correlated in a coherent phase-resolved way. Finally, we offer an explanation and solution for the ubiquitous low-frequency noise in IMU-based buoys and discuss necessary sampling and design to measure in areas of breaking waves.