Submesoscale to Mesoscale Variability in the California Current: Implications for SWOT

The dominant processes generating sea surface height (SSH) variability on the scales SWOT will measure (~10-100 km) vary by region and location. Interpreting SWOT data will thus require a priori knowledge about the spatial and temporal time scales of these different processes, their SSH signatures, and where in the water column the SSH variations originate. Here, we discuss strategies for unraveling the different contributions to SSH. We focus on the California Current, which is energetic across the scales that SWOT will measure. High-resolution model output from the 1/48-degree MITgcm simulation is used to quantify the partitioning of energy between mesoscale, submesoscale, and internal tides, and its spatial and seasonal variability. Submesoscale ocean variability, confined to the upper ~200 m of the water column, contributes significantly to SSH variability. We show that surface tracer fields are useful for quantifying the strength of submesoscale variability; implications for using satellite-based SST measurements as a complement to SWOT are discussed.