Examining the precipitation associated with medicanes in the high‐resolution ERA‐5 reanalysis data

Abstract

Medicanes, hurricane-like cyclonic systems in the Mediterranean Sea, are becoming an increasingly severe problem for many Mediterranean countries because climate projections suggest a higher risk under anthropogenic forcing even under an intermediate scenario. Due to the small size of these weather systems, high-resolution data are required to better resolve their structure and evolution. Here we investigate medicanes from the perspective of precipitation using the high-resolution (0.25) ERA-5 reanalysis data released by European Centre for Medium-Range Weather Forecasts. Overall, we identify a total of 59 medicanes from ERA-5 data during 1979-2017, with marked year-to-year variability. These storms tend to occur mostly between September and March. Overall, the intensity of medicanes (i.e., maximum wind) is lower than that of tropical cyclones, and this is also true for precipitation. The composite precipitation of medicanes increases from the centre to $0.8 and then decreases. During 1979-2017, many regions along the Mediterranean Sea experienced over 20 extreme precipitation events (i.e., days) which were caused by medicanes, accounting for 2-5% of all the extreme precipitation events.

Wind and wave extremes associated with tropical‐like cyclones in the Mediterranean basin

“…Both expressions in positive values indicate a warm‐core structure and a cold‐structure otherwise. These are calculated within a radius of 200 km around the minimum mean sea level pressure of the cyclonic centre (Zhang et al ., 2020).…”

“…Moreover, Zhang et al . (2020) used a similar range examining the precipitation associated with medicanes. Besides, the intention here is to quantify the extreme weather conditions during all stages of the event (not only during the tropical transition) and in distances greater than the cyclonic radius (~150–200 km).…”

“…of 200 km around the minimum mean sea level pressure of the cyclonic centre (Zhang et al, 2020). A cyclone, using the described criteria, is considered as a medicane when simultaneously the thermal symmetry factor is smaller than 10 and the thermal winds are both positive.…”

Characterization of medicanes with a minimal number of geopotential levels

“…climatological studies (e.g., Cavicchia et al, 2014a;Gaertner et al, 2018;Zhang et al, 2021). For the considered time period, we compute an annual mean of 1.17 cyclones and an increasing trend of 0.028 medicanes per year (see Table 2 for details).…”

Microstructure observations of the summer-to-winter destratification at a coastal site in the Gulf of Naples

“…The important role of lateral transport of freshwater in setting the stratification implies also that long term changes are possibly impacted also by the e↵ects of climate change on the surrounding territories, which include regions with important winter snow accumulations. Thus, the study area is an ideal site to study how coastal salinity and temperature changes combine in setting the variability of the vertical stratification (Woodson [2018]), in a context of rising air and sea temperatures and of intensifying extreme events such as storms, floods and even, recently, Mediterranean hurricanes (Volosciuk et al [2016], Koseki et al [2020], W. Zhang et al [2020]).…”