Thermodynamic Analysis of a Mediterranean Cyclone with Tropical Characteristics in the Central Mediterranean in September 2023

This study aims to conduct a dynamic analysis of a case of intense cyclogenesis that occurred in the central Mediterranean region during the period 07–11 September 2023. For a certain period, the system exhibited the structure of a Mediterranean cyclone with tropical characteristics (medicane). Before evolving into a medicane, the system also affected the Greek territory, causing extensive flooding in the region of Thessaly. It is considered an extreme meteorological event that significantly impacted the coastal areas of Libya and Egypt, with notable consequences for their economic and social structures, and stands as one of the most significant recorded medicane phenomena in the broader Mediterranean area. The synoptic and dynamic environment, as well as the thermodynamic structure of this atmospheric disturbance, were studied using thermodynamic parameters. The symmetry and warm-core structure of the system were demonstrated through phase-space diagrams, which define three distinct development phases of the system, each of which is further supported through dynamic analysis. During the first phase of the system, the configuration of the upper tropospheric layers was such that it began to reinforce the parent low-pressure system, which moved west–southwest, from the region of Greece toward the central Mediterranean. Therefore, the influence of upper-level dynamic processes was responsible for the reorganization of the weakened low-pressure system. In the second phase, when the Mediterranean cyclone was formed, low-level diabatic processes determined the evolution of the surface cyclone, without significant support from baroclinic processes in the upper troposphere. Thus, in this phase, the system is characterized as barotropic. During the third phase, the system remained barotropic but continued to show signs of weakening, as the sea-level pressure gradually increased.