Wide‐Swath Satellite Altimetry Data Improves Modeled Mesoscale and Submesoscale Dynamics in a Western Boundary Current

Abstract Ocean state estimates that represent mesoscale and submesoscale dynamics are crucial for climate research and ocean forecasting. Accurate submesoscale representation in ocean models is a current challenge due to rapidly evolving flow and lack of observations at suitable scales. The SWOT satellite provides a step change in ocean surface measurements at high spatial resolution (2 km). We use advanced data‐assimilation to demonstrate the impact of SWOT observations on circulation estimates in a high‐resolution hydrodynamic model of the East Australian Current. We show that assimilating SWOT data improves representation and prediction of the mesoscale motions, and improves representation (but not prediction) of the fine‐scale dynamics. Increased relative vorticity variance with SWOT assimilation is widespread in space and time (away from SWOT observations) and projected to depth. Using data observed by SWOT in a realistic ocean model, we show enhanced representation of ocean processes across scales, essential for improved ocean forecasts and projections.