TROPICAL-LIKE CYCLONES IN THE MEDITERRANEAN: IMPACTS AND COMPOSITE DAILY MEANS AND ANOMALIES OF SYNOPTIC CONDITIONS

摘要

In the Mediterranean region, a rapidly rotating storm system characterized by gale winds, severe precipitation, and low pressure center, accompanied with a spiral pattern of thunderstorms, is occasionally observed. Thus, these tropical-like cyclones (TLC), known as Medicanes or Mediterranean 'hurricanes', have similar characteristics with hurricanes and a significant research has been done during the last years to investigate their atmospheric characteristics and impacts.The Laboratory of Climatology and Atmospheric Environment (LACAE), University of Athens, has established a systematic effort since 2009, to document the impact of severe atmospheric phenomena (e.g. medicanes, cyclones, tornadoes, waterspouts), especially over the eastern Mediterranean region. Regarding medicanes, the best way to detect them is a direct visual analysis using satellite images to track and document these extreme phenomena occurred within the Mediterranean. The criteria applied in order to identify medicanes concern the detailed structure, the size and the lifetime of the systems using Meteosat satellite images in the infrared channel. They must have a continuous cloud cover and symmetric shape around a clearly visible cyclone eye. According to the above criteria and the international literature we have focused on 65 cases, which fulfilled the criteria of having a medicane.The objective of this study is twofold: (i) to illustrate the spatial and temporal distribution of TLC impacts over Mediterranean region and (ii) to present the composite daily means and anomalies of synoptic conditions at the middle and lower isobaric levels of the troposphere and sea level pressure (SLP), as well, during TLC days. The daily composite means and anomalies (with respect to 30 year climatology (1981-2010)) of synoptic conditions were based on the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis data sets. LACAE's data sets concern the period from 1947 to 2014, taken into account all TLC events and their impacts occurred over the western, central and eastern Mediterranean region.The findings shed light on the impacts of medicanes over coastal areas, including infrastructure damage and casualties due to associated strong winds, heavy rainfall, and in rare instances, tornadoes, indicating the high concern of such extreme atmospheric phenomena should be given by civil protection agencies towards resilience of the society.