Internal Waves Service: Towards Systematic Global Observation of Internal Solitary Waves

Oceanic energy budgets and mixing parameterizations are largely framed around tidal forcing, reflecting the availability of long-term, global datasets for barotropic and baroclinic tides. In contrast, internal waves, particularly Internal Solitary Waves (ISWs), remain poorly represented in global energy frameworks, despite their recognized role in transferring energy across scales, driving localized mixing, and modulating stratification. This imbalance is not only conceptual but observational: the lack of consistent, global datasets has limited the integration of internal wave processes into large-scale circulation and climate-relevant ocean models.

ISWs are nonlinear internal waves that propagate over long distances in stratified oceans, linking mesoscale and large-scale forcing to small-scale turbulence. Beyond their surface expressions observable from space, ISWs involve strong internal currents and large vertical displacements of isopycnals, with implications for offshore operations, marine structures, navigation, and ocean energetics. However, their transient nature and wide spatial extent make them particularly challenging to observe systematically, resulting in fragmented and geographically biased observational records.

We present the Internal Waves Service (IWS), which provides a first step towards addressing this gap, as a global, open, service-oriented framework for the systematic detection, mapping, and archiving of ISWs from satellite Earth Observation data. The service currently exploits synthetic aperture radar (SAR) imagery acquired by Sentinel-1 in Wave Mode, which provides unique, globally distributed observations of ISW surface signatures. Unlike traditional studies focused on specific regions or short time periods, the IWS processes all Sentinel-1 Wave Mode acquisitions on a continuous basis, enabling consistent global mapping of ISW presence and absence.

ISW detection is performed using an AI-assisted classification framework applied to SAR vignettes, supported by expert validation and iterative model refinement. The resulting products form a persistent, standardized dataset documenting spatial patterns and temporal variability of ISW activity across ocean basins.

By consolidating previously fragmented observations into a coordinated global dataset, the IWS provides a new observational basis for assessing the role of internal waves within ocean energy pathways. This systematic mapping supports comparative analyses, facilitates model evaluation, and opens the door to more consistent integration of internal wave processes alongside tides in multiscale ocean dynamics and energy budgets. Developed as a community-driven initiative involving 24 research institutions across 12 countries, the IWS is designed to evolve towards broader sensor integration and enhanced spatial coverage, strengthening its relevance for ocean modelling and climate studies.