The Internal Waves Service Workshop: Observing Internal Waves Globally with Deep Learning and Synthetic Aperture Radar

Oceanic internal solitary waves (ISWs) are long, powerful, nonlinear subsurface waves that propagate along sharp density gradients, typically near the seasonal or permanent pycnocline (Helfrich and Melville 2006). They can exceed 100 m in amplitude at depth, with periods from minutes to under an hour, producing strong vertical velocities (>0.5 m s−1) and localized shear currents. ISWs are usually generated from linear internal tides that steepen into solitary waves, typically when barotropic tidal flows displace stratified layers over sloping topography. When forcing is strong enough, baroclinic energy can quickly cascade into nonlinear waves. Other mechanisms include wind forcing, gravity currents, and interactions with mesoscale oceanic features (e.g., Buijsman et al. 2010; Jackson et al. 2012; Lamb 2014; da Silva et al. 2015). ISWs often appear in wave trains of solitons (Apel et al. 1975; Osborne and Burch 1980; Alford et al. 2015), ranked by amplitude and visible in high-resolution satellite observations in optical, altimeter, and synthetic aperture radar (SAR). Given the ocean’s vastness and limited in situ observations, satellite remote sensing has long been key to ISW monitoring. The advent of satellites equipped with SAR in the 1980–90s revolutionized ISW research by providing high-resolution, two-dimensional, day-and-night, all-weather observations of surface signatures (Fu and Holt 1982; Alpers 1985). However, identifying these waves in satellite imagery remains labor-intensive due to the sheer volume of data. To address this challenge, the Internal Waves Service (IWS) was conceived, a deep learning–based system that automatically detects and logs internal wave events, making the data openly accessible. To promote the IWS and gather feedback, the Atlantic International Research Centre (AIR Centre) organized the IWS Workshop 2025 (IWS-W25), held on 3–4 April 2025 in Angra do Heroísmo, Azores, Portugal. The event gathered 15 invited researchers, oceanographers, and data service providers from institutions across Europe and North America to discuss IWS development. The IWS initiative aims to enhance detection, forecasting, and understanding of internal wave dynamics, which are critical for advancing operational oceanography and climate research. Currently, it uses SAR Wave (WV) mode data from the European Space Agency’s (ESA’s) Sentinel-1 satellite mission, offering near-real-time, global, open-ocean coverage with a latency of approximately four days. Expert-validated deep learning algorithms classify ISWs, supporting the first operational, long-term global ISW monitoring service.