Observations of Large-Amplitude Nonlinear Internal Waves from a Drifting Array: Instruments and Methods

Abstract

Abstract This paper presents a novel methodology applied to the observation of large-amplitude nonlinear internal waves in the upper ocean from an array of drifting instruments. The characteristics of the instrument used—an Autonomous Drifting Ocean Station with acoustic current profilers (ADOS-A), which is a drifting buoy with a 200-m-long thermistor chain, several profiling acoustic current meters, and a GPS—are discussed. The ADOS-A is lightweight and relatively inexpensive and can be deployed from aircrafts or from ships of opportunity. Three packets of large-amplitude, nonlinear internal waves were observed in the South China Sea. The speed and the direction of propagation of the waves are accurately determined and their characteristics and evolution over space and time scales comparable with those of the waves, as they propagate through the array, are discussed.