Title: Use of SWOT data to improve ocean prediction models

The SWOT satellite successfully launched on December 16, 2022 will extend the capability of existing nadir altimeters to two-dimensional mapping of Sea Surface Height (SSH) at a much higher resolution. This will allow observing mesoscale and submesoscale signals for wavelengths between 20 and 200 km. Mercator Ocean International (MOi) has conducted several Observing System Simulation Experiments (OSSEs) to assess the potential of SWOT and more generally swath altimetry for ocean forecasting. The main objective of this PhD thesis will be to work with the first SWOT data and to demonstrate how SWOT improves ocean prediction capabilities at different space and time scales.

SWOT data from the fast-sampling phase (1 day) will be first analyzed and compared to MOi modelling and data assimilation systems to characterize the SSH variability at different space and time scales seen in the model and SWOT observations. Assimilation of SWOT data from the fast sampling (1-day) phase in the global data assimilation system will then be carried out and results will be analyzed over the SWOT crossover regions. The one-day fast sampling phase will offer a unique opportunity to assess the model forecast representation of the high frequency phenomena down to 1-day that will be aliased with the 21-day orbit. The final task will deal with the assimilation of SWOT data from the nominal 21- day sampling phase. When moving to the 21-day phase, the capacity of the model dynamic to dynamically propagate the “instantaneous” SSH information to the next revisiting time will be analyzed. Diagnostics to assess the impact of SWOT for ocean analyses and forecasts at different space and time scales will be developed by comparing assimilation results with and without SWOT. New data assimilation techniques developed at MOI (multi-scale, ensemble approaches) will also be tested. Ensemble approaches will be used, in particular, to assess the predictability of mesoscale/submesocale signals.

Link: https://www.mercator-ocean.eu/offres-d-emploi/