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

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.