A study led by Elisabet Verger, a predoctoral researcher at the Mediterranean Institute for Advanced Studies (Imedea), has shed new light on the behaviour of a small rotating water current to the north-west of Mallorca, a strategically important area for the dynamics of the Balearic Sea. The research demonstrates how a new-generation satellite can detect fine-scale marine structures that were largely invisible to earlier observation systems.
The work is based on data from the Surface Water and Ocean Topography (SWOT) satellite, launched in December 2022, which is capable of mapping the ocean surface with unprecedented detail in the Mediterranean. During the mission’s initial commissioning phase, scientists combined satellite observations with direct measurements at sea, including underwater gliders, drifting buoys and current meters deployed in the western Mediterranean.
These measurements confirmed the presence of an anticyclonic ocean whirlpool with a radius of about 25 kilometres, located beneath the ocean’s surface layer. Currents of up to 30 centimetres per second were recorded at depths exceeding 150 metres, revealing a powerful and dynamic structure that had proved difficult to identify using previous satellite technologies.
By comparing SWOT data with conventional satellite observations, the researchers found a marked improvement in accuracy. Errors in sea-level estimates were reduced by around 24%, while calculations of current speeds improved by between 30% and 35%. This leap in precision is largely due to SWOT’s spatial resolution, which is up to ten times higher than that of earlier missions.
Scientists say the findings will improve understanding of how sea swirls influence circulation and the exchange of heat, water and nutrients—processes that play a crucial role in climate regulation and marine ecosystems. The study places the Balearic Sea and Mallorca at the forefront of international oceanographic research and confirms SWOT as a major advance in satellite-based observation, with implications that extend well beyond the Mediterranean.