What is the role of fine scales in horizontal and vertical exchange in the upper ocean? 

 FaSt-SWOT study area. The white rectangle indicates the experimental area south of the island of Mallorca in the western Mediterranean Sea. The colored areas indicate the location of HF radars. The fast-sampling SWOT swaths are represented by the transparent bands. The background colored arrows represent the WMOP model streams for 6 Nov 2021. Source: IBISAR viewer. Figure author: Emma Reyes.

Horizontal and vertical motions associated with fine scale ocean features (10-100 km), such as mesoscale and submesoscale fronts, meanders, eddies and filaments, are of fundamental importance for the distribution of heat, salt, gasses, carbon and nutrients in the ocean, thus impacting the way the ocean regulates the changing Earth’s climate.    Understanding the three-dimensional (3D) dynamics associated with fine scale features and their impact on the large scale ocean circulation and climate system is one of the major international challenges for the next decade in oceanography. During the last decades, remote sensing observations of sea surface height (SSH) have significantly increased our understanding of the global ocean’s large and mesoscale circulation; eddy identification and tracking, and quantification of eddy kinetic energy. Satellite altimetry observations have the advantage of covering the global ocean in short periods of time.  However, the effective resolution of present gridded SSH maps is limited, i.e. ~130 km in the Mediterranean Sea, which is still insufficient to resolve the entire range of mesoscale dynamics which develop over shorter temporal and spatial scales in this basin compared to the open ocean.

The western Mediterranean Sea is a natural reduced-scale laboratory basin for the examination of processes of global importance and the FaSt-SWOT (Fine-Scale ocean currents from integrated multi-platform experiments and numerical simulations: contribution to the new SWOT satellite mission) campaign will take place in the Balearic Sea during the SWOT fast-sampling phase. The general objective of the campaign is to improve the characterization of oceanic fine scales through the combined use of in-situ multi-platform and satellite data in synergy with numerical models and innovative computational techniques. Gathering a unique multidisciplinary expertise in physical oceanography, satellite remote sensing, in situ monitoring and computational science, the campaign will assess the actual capability to map SSH variability over a range of scales (30-100 km) traditionally not resolved by conventional altimeters.

A unique aspect of the FaSt-SWOT campaign is the combination of concurrent multi-scale ship-based, autonomous platform, and satellite observations with ad hoc modeling simulations, enabling the evaluation of underlying mechanisms. Taking advantage of the unique observing and high-resolution data-assimilative modeling capacities developed by IMEDEA and SOCIB teams over the recent years, FaSt-SWOT aims to take a step further supporting the analysis and exploitation of the first SWOT high- resolution measurements. The project federates two multiplatform synoptic in situ experiments, combining glider, drifter, ship and HF radar observations together with satellite observations and high-resolution data-assimilative numerical simulations. Advanced Observing System Simulation Experiments will be performed to optimize the sampling strategies. New tools of artificial intelligence will be developed and applied to enhance the synergy of in-situ and SWOT data. Moreover, SWOT data assimilation will be implemented to integrate this new data set into operational ocean prediction systems. Overall, these different tools will be combined to retrieve and analyze fine-scale horizontal and vertical currents.

Integrated approaches combining multi-platform in-situ data with remote sensing observations and high-resolution model simulations constitute the innovative methodology proposed to evaluate and understand the 3D pathways associated with fine scale structures.  The study of the Balearic  region is of special interest given that the Mediterranean Sea is recognized as an ideal laboratory for studying ocean processes of global relevance, such as water mass formation, overturning circulation, boundary currents, meso/submesoscale eddies and instabilities, carbon export and associated ecosystem responses. 

Principal investigators:  Ananda Pascual (IMEDEA, Spain) and Baptiste Mourre (SOCIB, Spain)

Institutes involved in the campaign: IMEDEA, SOCIB 

Contact point for the study site: Ananda Pascual (

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