The FaSt-SWOT experiments aim to integrate SWOT measurements with in-situ observations from two high-resolution multi-platform ocean campaigns and advanced data-assimilative models. The goal is to evaluate the performance of the satellite, characterize fine-scale (10-100 km) dynamics and quantify the associated horizontal and vertical transports. The FaSt-SWOT experiments were specifically designed to collect multi-platform in-situ observations within the swath of the SWOT satellite for validation, focusing on the area around the Balearic Sea. The campaigns took place in April and May 2023 and involved the simultaneous use of various ship-based instruments (CTD, Moving Vessel Profiler (MVP), thermosalinograph, ADCP, GoPros), autonomous platforms (surface drifters and gliders), and satellite observations (SST, ocean color, altimetry).

In this presentation, we will focus on the analysis and processing of the multi-platform data collected during FaSt-SWOT. The sampling location was defined a few days before the first experiment based on the presence of a remarkable small-scale anticyclonic eddy (~20 km-diameter) detected in SST imagery and in the trajectory of a drifter within one of the SWOT swaths north of the Ibiza Island. Subsequent SST and ocean color maps showed the temporal evolution of the sampled eddy, which evolved into finer-scale features. Therefore, the context was ideal for analyzing SWOT's capability to detect this type of small structures. Indeed, the signature of the eddy was detected in the first sea level maps provided by SWOT and unresolved by conventional altimetry.

The analyzed data consist of ~1000 MVP profiles of temperature and salinity from the surface down to a depth of 200 m along the ship trajectory (100 m during the first phase), combined with CTD rosette casts at fixed stations down to 700 m depth. Additionally, we will present data from two gliders that conducted 2 back-and-forth transects along the satellite swath with a 1-day delay between them, and the data from the 45 surface drifters deployed during both phases of the experiment. We will discuss the processing of the MVP observations, as well as the cross-calibration performed between CTD, MVP, and gliders measurements. This is a really important step to ensure that we are providing accurate and reliable quality-controlled observations, as well as a necessary process since these data will be available. Finally, we will provide a comparison between in-situ observations and SWOT data, and an analysis of the dynamics in the sampled area.