Analysis of the environments of seven Mediterranean tropical-like storms using an axisymmetric, nonhydrostatic, cloud resolving model

Abstract

Abstract. Tropical-like storms on the Mediterranean Sea are occasionally observed on satellite images, often with a clear eye surrounded by an axysimmetric cloud structure. These storms sometimes attain hurricane intensity and can severely affect coastal lands. A deep, cut-off, cold-core low is usually observed at mid-upper tropospheric levels in association with the development of these tropical-like systems. In this study we attempt to apply some tools previously used in studies of tropical hurricanes to characterise the environments in which seven known Mediterranean events developed. In particular, an axisymmetric, nonhydrostatic, cloud resolving model is applied to simulate the tropical-like storm genesis and evolution. Results are compared to surface observations when landfall occurred and with satellite microwave derived wind speed measurements over the sea. Finally, sensitivities of the numerical simulations to different factors (e.g. sea surface temperature, vertical humidity profile and size of the initial precursor of the storm) are examined.

Tropical transition of a Mediterranean storm by jet crossing

“…Among the Mediterranean cyclones accompanied by upper-level anomalies and deep convection, about 15 mesocyclones have been observed over the last 20 years, preferentially in autumn (Fita et al, 2007). They share some similarities with tropical cyclones and a number of case studies have been made on these hurricanelike cyclones or medicanes (Mediterranean 'hurricanes'; Lagouvardos et al, 1999;Pytharoulis et al, 2000;Reale and Copyright c 2011 Royal Meteorological Society Atlas, 2001;Homar et al, 2003;Fita et al, 2007;Moscatello et al, 2008aMoscatello et al, , 2008bDavolio et al, 2009;Claud et al, 2010;McTaggart-Cowan et al, 2010;among others). A medicane exhibits a clearly defined eye, quasi-circular cloud patterns, strong surface winds sometimes reaching the intensity of a tropical storm, deep convection and the presence of a warm core.…”

“…The vortex is accompanied by deep convection and a deep, cutoff, cold core is usually observed at mid-upper tropospheric levels (e.g. Reale and Atlas, 2001;Fita et al, 2007), which triggers the convective instability (e.g. Reale and Atlas, 2001;Homar et al, 2003;Pytharoulis et al, 2000).…”

Simulation of medicanes over the Mediterranean Sea in a regional climate model ensemble: impact of ocean–atmosphere coupling and increased resolution

“…Their diameter is rather small, typically less than 300 km and they generally present a symmetrical cloud structure around a cloudless eye (Fita et al 2007), which indicates tropical characteristics like a warm core and a predominant role of air-sea fluxes and convection in their development and maintenance. They form from baroclinic cut-off lows, evolving into a warm core cyclone through tropical transition (Emanuel 2005;Chaboureau et al 2012).…”

Impact of Sea Surface Temperature on COSMO Forecasts of a Medicane over the Western Mediterranean Sea

“…In recent years, the scientific community has started to detect and analyze tropical-like cyclones in the Mediterranean Sea [1]. The Mediterranean is a large and sometimes warm body of water, thus it can be an area of cyclogenesis influenced by convective instability and air-sea interaction, producing cyclones with some of the characteristics of hurricanes [2,3].…”

“…These cyclones are characterized by strong winds and a pressure minimum in the middle (calm eye). Such systems are referred in the literature as Medicanes (Mediterranean Hurricanes) and are rare phenomena (only one or two per year) [1,5].…”