Kydd Pollock (The Nature Conservancy, USA); Dimitris Menemenlis (San Jose State University/Moss Landing Marine Lab, USA); Santha Akella (NOAA, USA); Brian Arbic (University of Michigan, USA); Morgan Gilmour (NASA Ames, USA)

This project advances understanding of how submesoscales (~10–500 km) contribute to equatorial Pacific Ocean circulation and ENSO variability using SWOT KaRIn sea-surface height observations, high-resolution ocean simulations, and in situ drifter-based measurements of surface currents. We quantify submesoscale sea-level variability across the tropical Pacific, focusing on its modulation by the 2023–2024 ENSO event. Detailed analyses focus on the north central equatorial Pacific and especially the vicinity of Palmyra Atoll, where 32 drifters have been released in clusters during eight deployments from August 2024 to June 2025 and about 100 drifter releases are planned over 18 deployments through at least June 2026. The local analysis of the relationship between currents and heights also contributes to a NASA ecological conservation project aimed at forecasting drifting fish aggregating device (dFAD) trajectories to protect coral reef ecosystems. The broader investigation of the role of submesoscales in the regional ocean circulation and ENSO aims to develop quantitative constraints on submesoscale processes that can guide the development of improved global atmosphere-ocean models.