ergane fouchet (Mercator-Ocean International, France); Pierre-Yves Le Traon (Mercator-Ocean International, France)

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 results have shown that the complementarity of SWOT with night-time data improves the quality of ocean forecasts. The launch of the SWOT satellite took place on 16 December 2022. We used the last version of SWOT (v2.0.1) data (nadir+karin) to carry out the assimilation of these data in our global (1/12°) forecasting system. We highlight the contribution of SWOT to global system forecasting. A new data assimilation technique with scale separation has been tested at MOi. Adding SWOT observations to those of others nadir altimeters globally reduces the variance of Sea Level Anomaly by 20%, respectively. We present the impact of SWOT (21-days Orbit) data assimilation on ocean forecast quality. We test new metrics to highlight the impact of SWOT data using independent data.