Mediterranean cyclones: current knowledge and open questions on dynamics, prediction, climatology and impacts

Flaounas, Emmanouil; Davolio, Silvio; Raveh‐Rubin, Shira; Pantillon, Florian; Miglietta, Mario Marcello; Gaertner, Miguel Ángel; Hatzaki, Maria; Homar, V.; Khodayar, S.; Κορρές, Γεράσιμος; Kotroni, Vassiliki; Kushta, Jonilda; Reale, Marco; Ricard, Didier

doi:10.5194/wcd-3-173-2022

Cited by 96 publications

(85 citation statements)

References 263 publications

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“…Case studies revealed the crucial role of mountains for the formation of specific cyclones, as almost the entire PV was produced near them. Therefore, the resolution of diabatic processes near mountains is crucial for correctly predicting the intensity of cyclones, as previously highlighted by Flaounas et al (2022). Our climatological study confirmed that the lower-tropospheric PV anomaly can be produced to a large degree in the environment.…”

Section: Discussionsupporting

confidence: 83%

“…The Mediterranean is one of the most cyclogenetic region in the world (Trigo et al, 1999;Ulbrich et al, 2009;Neu et al, 2013). Mediterranean cyclones are prominent high-impact weather systems that have been increasingly analyzed in the last years and thus, the driving processes of genesis and intensification of Mediterranean cyclones are fairly well known (Flaounas et al, 2022). They typically form in response to upper-tropospheric systems, such as potential vorticity (PV) cutoffs or narrow, meridionally-extended troughs that correspond to PV streamers (Appenzeller and Davies, 1992).…”

Section: Introductionmentioning

confidence: 99%

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Origin of low-tropospheric potential vorticity in Mediterranean cyclones

Scherrmann

Wernli

Flaounas

2022

Preprint

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Abstract. Mediterranean cyclones are extratropical cyclones, typically of smaller size and weaker intensity than other cyclones that develop over the main open ocean storm tracks. Nevertheless, Mediterranean cyclones can attain high intensities, even comparable to the ones of tropical cyclones, and thus cause large socio-economic impacts in the densely populated coasts of the region. After cyclogenesis takes place, a large variety of processes are involved in the cyclone’s development, contributing with positive and negative potential vorticity (PV) changes to the lower-tropospheric PV anomalies in the cyclone center. Although the diabatic processes that produce these PV anomalies in Mediterranean cyclones are known in principle, it is still an open question whether they occur locally within the cyclone itself or remotely in the environment (e.g., near high orography) with a subsequent transport of high-PV air into the cyclone center. This study introduces a Lagrangian method to determine the origin of the lower-tropospheric PV anomaly, with an average amplitude of 1.2 PVU, relative to the tracks of cyclones identified in ERA5 reanalyses. We define and quantify so-called "cyclonic" and "environmental" PV and find that the main part of the lower-tropospheric PV anomaly (60 %) is produced within the cyclone, shortly prior (-12 h) to the cyclones mature stage. Nevertheless, in 10 % of the cyclones the environmental PV production near the mountains surrounding the Mediterranean basin plays the dominant role for the low-tropospheric PV anomaly, and therefore the intensity of the circulation associated with these cyclones. An additional investigation of IFS simulations with detailed output from physical parameterizations reveals that the major PV production inside the cyclone is typically due to convection and large-scale microphysics, whereas convection and turbulent momentum tendencies evoke most of the positive PV changes found in the environment.

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Section: Discussionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Origin of low-tropospheric potential vorticity in Mediterranean cyclones

Scherrmann

Wernli

Flaounas

2022

Preprint

Self Cite

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“…Three of these, called Qendresa (2014), Zorbas (2018), and Apollo (2021), strongly impacted the coast of south-eastern Sicily, in particular in Massolivieri, Maddalena Peninsula, and Varco 11 (Figure 2), with duration ranging from 4 to 7 days. As the Ionian Sea is not an area eligible for the formation of Tropical Cyclones, these phenomena occur due to a Tropical Transition (TT) process that can change an extratropical system into a tropical system or induce a hybrid cyclone [47,48]. However, several authors predict that, soon, climate changes could modify medicanes, decreasing the frequency of their occurrence but increasing the strength of their impacts [49].…”

Section: Geographic Frameworkmentioning

confidence: 99%

Convolutional Neural Network and Optical Flow for the Assessment of Wave and Tide Parameters from Video Analysis (LEUCOTEA): An Innovative Tool for Coastal Monitoring

Scardino

Scicchitano

Chirivì³

et al. 2022

Remote Sensing

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Coastal monitoring is a topic continuously developing, which has been applied using different approaches to assess the meteo-marine features, for example, to contribute to the development of improved management strategies. Among these different approaches, coastal video monitoring coupled with recent machine learning and computer vision techniques has spread widely to assess the meteo-marine features. Video monitoring allows to obtain large spatially and temporally datasets well-distributed along the coasts. The video records can compile a series of continuous frames where tide phases, wave parameters, and storm features are clearly observable. In this work, we present LEUCOTEA, an innovative system composed of a combined approach between Geophysical surveys, Convolutional Neural Network (CNN), and Optical Flow techniques to assess tide and storm parameters by a video record. Tide phases and storm surge were obtained through CNN classification techniques, while Optical Flow techniques were used to assess the wave flow and wave height impacting the coasts. Neural network predictions were compared with tide gauge records. Furthermore, water levels and wave heights were validated through spatial reference points obtained from pre-event topographic surveys in the proximity of surveillance cameras. This approach improved the calibration between network results and field data. Results were evaluated through a Root Mean Square Error analysis and analyses of the correlation coefficient between results and field data. LEUCOTEA system has been developed in the Mediterranean Sea through the use of video records acquired by surveillance cameras located in the proximity of south-eastern Sicily (Italy) and subsequently applied on the Atlantic coasts of Portugal to test the use of action cameras with the CNN and show the difference in terms of wave settings when compared with the Mediterranean coasts. The application of CNN and Optical Flow techniques could represent an improvement in the application of monitoring techniques in coastal environments, permitting to automatically collect a continuous record of data that are usually not densely distributed or available.

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“…All of the above can increase the frequency and intensity of adverse cyclone-related hydrometeorological and hydrological events, for example torrential precipitation, wind surges, severe river floods, landslides [3]. Considering these risks, the Mediterranean Basin is particularly vulnerable to climate change [4].…”

Section: Introductionmentioning

confidence: 99%

“…On the one hand, an increase in sea surface temperatures and latent heat fluxes increase convection, therefore thermodynamic processes become more important. On the other hand, higher temperature increase in the upper troposphere increases atmospheric stability [3,4]. In addition, a warmer atmosphere can hold more moisture according to the Clausius-Clapeyron equation [3], which is expected to lead to increased water vapor transport [5] and cyclone-related precipitation [6,7], for example over the Western Atlantic and Mediterranean region [8].…”

Section: Introductionmentioning

confidence: 99%

Present and future changes of winter cyclonic activity in the Mediterranean-Black Sea region in the 21st century in CMIP6 models’ ensemble

Voskresenskaya¹,

Maslova²,

Lubkov³

et al. 2022

Preprint

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A better understanding of the expected future cyclonic activity, especially in the Mediterranean Basin in winter, is essential for developing scientifically based adaptation and mitigation methods to extreme precipitation and wind anomalies. The aim of this study is to analyze the change of winter cyclonic activity in the Mediterranean-Black Sea region, within the Atlantic–European region, at the beginning (as the recent historical period), middle and end of the 21st century. The projections are based on an ensemble of seven CMIP6 models, which showed the best consistency with NCEP/NCAR and ERA5 reanalysis, under the intermediate SSP2-4.5 and highest-emission SSP5-8.5 scenarios. The results show a consistent increase of the frequency of cyclones over Central Europe and the British Isles associated with the shift of cyclone tracks: norward from the Western Mediterranean region and southward from the Iceland Low. The latter leads to a decrease of the frequency in the north of the Atlantic–European region. At the same time, there is a reduction of the frequency of cyclones over the east of the Mediterranean Sea consistent with the decrease of cyclogenesis events. Area-averaged cyclone numbers in the Western and Eastern Mediterranean and the Black Sea subregions reduce to the end of the century under the highest-emission scenario, but not constantly and with a raise in the middle of the 21st century under both scenarios, which may be linked to the long-term multidecadal variability or regional features. In general, our study shows that the future winter cyclonic activity in the Mediterranean-Black Sea region responds unevenly to global climate changes, because regional and monthly features are important, as well as accounting for the long-term quasiperiodic variability.

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Mediterranean cyclones: current knowledge and open questions on dynamics, prediction, climatology and impacts

Cited by 96 publications

References 263 publications

Origin of low-tropospheric potential vorticity in Mediterranean cyclones

Origin of low-tropospheric potential vorticity in Mediterranean cyclones

Convolutional Neural Network and Optical Flow for the Assessment of Wave and Tide Parameters from Video Analysis (LEUCOTEA): An Innovative Tool for Coastal Monitoring

Present and future changes of winter cyclonic activity in the Mediterranean-Black Sea region in the 21st century in CMIP6 models’ ensemble

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