Presenter: M Archer (Jet Propulsion Laboratory)

Description:
The Surface Water and Ocean Topography (SWOT) satellite will be launched in winter 2022 to measure sea surface height (SSH) in two-dimensional swaths over the global ocean. SWOT will have unprecedented sub-centimeter accuracy that offers exciting opportunities to study small-mesoscale ocean dynamics via SSH variability at scales of 15–150-km. However, the 21-day-repeat cycle of the science orbit leaves large spatial and temporal gaps between swaths. These measurement gaps pose a challenge for characterizing the transient small-scale ocean dynamics. Data assimilation (DA) will therefore play a crucial role in SWOT science applications, as well as in the post-launch mission Calibration/Validation (Cal/Val) effort. “ECCO-SWOT” is a high-resolution DA system built upon the MITgcm-ECCO adjoint framework, nested within the synoptic California short-term State Estimate. It has 1-km resolution and covers a 200-km x 200-km area of the California Current system at the location of the SWOT CalVal site, 300-km offshore of Monterey Bay. Here we evaluate its performance using a set of in-situ measurements collected during the SWOT prelaunch field campaign (Sep 2019 – Jan 2020). This ECCO-SWOT experiment demonstrates the feasibility of using a high-resolution adjoint-based DA to support the mission Cal/Val and paves the way to assimilating the high-resolution SWOT SSH measurements.