Recent data assimilation developments in the Mediterranean Sea Analysis and Forecasting System (MedFS)

The Mediterranean Sea Analysis and Forecasting System (MedFS) is continuously under development to provide improved ocean state estimates and daily forecasts through the Copernicus Marine Service. Since the beginning of the second phase of Copernicus Marine Service, there have been various upgrades in the data assimilation (DA) component of the MedFS and assimilated observations. MedFS consists of a NEMO-based modelling system coupled with WW3 for improved hydrodynamic representation and it is interfaced to OceanVar, the CMCC 3D variational ocean data assimilation scheme to incorporate observations. Here we present the most important novelties recently included in the operational system which consist in the use of a new observation-based Mean Dynamic Topography (MDT) and a new set of Empirical Orthogonal Functions (EOFs) computed from 35 years of Mediterranean high-resolution reanalysis both covering also the Atlantic side of the domain, as well as the ingestion of Sentinel-6A Sea Level anomaly (SLA) altimeter data. An initial assessment of the assimilation of 5 Hz (~1 km) SLA observations will be presented. Moreover, we will show the impact of the assimilation of glider observations in the Mediterranean Sea with a focus on the western basin. Finally, we will outline our future plans for this phase of the Copernicus Marine Service towards higher-frequency assimilation with an improved background representation and observation operators for satellite products.