Getting to the core of a medicane
A research team led by Italy’s National Research Council Institute of Atmospheric Sciences and Climate (CNR‑ISAC) and funded through the European Space Agency’s Earth Observation Science for Society Medicanes Project published a standardized definition of Mediterranean hurricanes, or medicanes, and applied it to the storm that struck Libya in mid‑March 2024. The system, originally identified as the cold‑core low‑pressure area Samuel on 14 March over the western Mediterranean, was reclassified as Medicane Jolina on 17 March as it acquired tropical‑like characteristics and made landfall in Libya on 19 March. The study, appearing in the Bulletin of the American Meteorological Society, provides a clear classification framework for a phenomenon that affects more than 500 million people around the Mediterranean basin.
The classification relied on a suite of Earth‑observation assets. Visible and infrared imagery from Meteosat Third Generation and Meteosat Second Generation geostationary satellites captured the spiral cloud bands and the emergence of an eye‑like, cloud‑free centre as the storm approached land. Microwave sounders—MetOp‑C’s AMSU‑A and the Advanced Technology Microwave Sounders on NOAA‑20 and NOAA‑21—recorded the development of a warm core extending into the upper troposphere, a key criterion of the new definition. Surface wind structure and intensity were derived from MetOp’s ASCAT scatterometer and Copernicus Sentinel‑1 synthetic‑aperture radar, which identified a near‑closed ring of sea‑surface wind, measured maximum sustained wind speeds, and determined the radius of maximum wind. The definition specifies a mesoscale cyclone with a warm core, an eye‑like feature, symmetric sea‑surface wind circulation, and peak winds located within a few tens of kilometres from the centre. Jolina’s transition from a cold‑core to a warm‑core system occurred despite relatively low sea‑surface temperatures, underscoring the role of both tropical and mid‑latitude processes in medicane formation.
The Jolina case illustrates the broader implications of a unified medicane taxonomy and near‑real‑time satellite monitoring. Historically, the rarity of medicanes—occurring up to three times per year—has limited observational data and hampered model validation, leading to inconsistent warnings. By establishing observable, satellite‑based criteria, the new definition enables more reliable tracking, intensity estimation, and early‑warning dissemination, which can mitigate socio‑economic impacts. The storm prompted school closures in Sicily and Calabria, caused structural damage and flight cancellations in Catania, and generated severe flooding in Libyan cities such as Tajoura and Zawiya, where a fatality was recorded. These effects highlight the vulnerability of coastal infrastructure and emergency services to even moderate‑intensity medicanes. The successful application of multi‑sensor Earth observation to Jolina therefore advances both scientific understanding of Mediterranean cyclones and practical risk‑management capabilities for the region.
