SFY—A Lightweight, High-Frequency, and Phase-Resolving Wave Buoy for Coastal Waters

Abstract

Small lightweight wave buoys, 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 bandwidth. The low cost and low weight permit 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 the breaking waves of the surf. The conditions range from calm to significant wave heights exceeding 7 m and crashing breakers with accelerations exceeding 10g. 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 inertial measurement unit (IMU)–based buoys and discuss the necessary sampling and design to measure the areas of breaking waves.