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The study of atmospheric models and climate systems has been hampered by the restricted availability of wind profile measurements. By recording wind profiles in near real time and giving useful information for Numerical Weather Prediction (NWP) models, the Doppler wind lidar technology used in the European Space Agency's Aeolus mission is expected to unravel this problem. By analyzing the precipitation from IANOS medicane, which occurred over the Thessaly plain in September 2020, a case study utilizing the COSMO NWP model illustrates the potential usefulness of Aeolus data in strengthening NWP models. Run in hindcast mode and forced by analyses with and without Aeolus, the model assimilated data that were produced at the European Centre for Medium-Range Forecasts (ECMWF). Evaluation against observations from Greek synoptic stations showed that the model precipitation using the Aeolus-assimilated data preponderated over the model results without their inclusion. This work aims to demonstrate the additional value of the Aeolus project towards the expansion of our knowledge of Earth's atmosphere, particularly the improvement of our capacity to estimate severe weather events via the use of Aeolus with NWP models. [ABSTRACT FROM AUTHOR]

Mediterranean hurricanes (Medicanes) are characterized by the presence of a quasi-cloud-free calm eye, spiral-like cloud bands, and strong winds around the vortex center. Typically, they reach a tropical-like cyclone (TLC) phase characterized by an axisymmetric warm core without frontal structures. Yet, some of them are not fully symmetrical, have a shallow warm-core structure, and a weak frontal activity. Finding a clear definition and potential classification of Medicanes based on their initiation and intensification processes, understanding the role of convection, and identifying the evolution to a TLC phase are all current research topics. In this study, passive microwave (PMW) measurements and products are used to characterize warm core (WC) and deep convection (DC) for six Medicanes that occurred between 2014 and 2021. A well-established methodology for tropical cyclones, based on PMW temperature sounding channels, is used to identify the WC while PMW diagnostic tools and products (e.g., cloud-top height (CTH) and ice water path (IWP)), combined with lightning data, are used for DC detection and characterization. The application of this methodology to Medicanes highlights the possibility to describe their WC depth, intensity, and symmetry and to identify the cyclone center. We also analyze to what extent the occurrence and characteristics of the WC are related to the Medicane's intensity and DC development. The results show that Medicanes reaching full TLC phase are associated with deep and symmetric WCs, and that asymmetric DC features in the proximity of the center, and in higher CTH and IWP values, with scarce lighting activity. Medicanes that never develop to a fully TLC structure are associated with a shallower WC, weaker and more sparse DC activity, and lower CTHs and IWP values. Ultimately, this study illustrates the potential of PMW radiometry in providing insights into dynamic and thermodynamic processes associated with Medicanes' WC characteristics and evolution to TLCs, thus contributing to the ongoing discussion about Medicanes' definition. [ABSTRACT FROM AUTHOR]

The rotating-convection paradigm for tropical cyclone behaviour is shown to provide an attractive and consistent framework for interpreting the dynamics of formation and intensification of at least some medicanes. The ideas are illustrated by a case study of the medicane that formed over the eastern Mediterranean in mid-December 2020. This case study is based on analyses of data from the European Centre for Medium Range Weather Forecasts (ECMWF), imagery from the European geostationary meteorological satellite, Meteosat Second Generation, and output from a convection permitting numerical simulation of the event using the United Kingdom (UK) Met Office regional model with the RAL2 physics configuration. Limitations of the currently widely accepted interpretation of medicanes in terms of the so-called Wind-Induced Surface Heat Exchange (WISHE) intensification mechanism are discussed.

Mediterranean hurricanes, or medicanes, are tropical-like cyclones forming once or twice per year over the waters of the Mediterranean Sea. These mesocyclones pose a serious threat to coastal infrastructure and lives because of their strong winds and intense rainfall. Infrasound technology has already been employed to investigate the acoustic signatures of severe weather events, and this study aims at characterizing, for the first time, the infrasound detections that can be related to medicanes. This work also contributes to infrasound source discrimination efforts in the context of the Comprehensive Nuclear-Test-Ban Treaty. We use data from the infrasound station IS48 of the International Monitoring System in Tunisia to investigate the infrasound signatures of mesocyclones using a multi-channel correlation algorithm. We discuss the detections using meteorological fields to assess the presence of stratospheric waveguides favoring propagation. We corroborate the detections by considering other datasets, such as satellite observations, a surface lightning detection network, and products mapping the simulated intensity of the swell. High- and low-frequency detections are evidenced for three medicanes at distances ranging between 250 and 1100 km from the station. Several cases of non-detection are also discussed. While deep convective systems, and mostly lightning within them, seem to be the main source of detections above 1 Hz, hotspots of swell (microbarom) related to the medicanes are evidenced between 0.1 and 0.5 Hz. In the latter case, simulations of microbarom detections are consistent with the observations. Multi-source situations are highlighted, stressing the need for more resilient detection-estimation algorithms. Cloud-to-ground lightning seems not to explain all high-frequency detections, suggesting that additional sources of electrical or dynamical origin may be at play that are related to deep convective systems. [ABSTRACT FROM AUTHOR]

Medicanes, a type of strong hurricanes/cyclones occurring in the Mediterranean, can be the source of major geohazard events in Mediterranean coastal and inland areas. Medicane Ianos that hit Greece during 17–19 September 2020 caused widespread damage, with numerous landsides and floods being the most prominent. Following the landfall of Medicane Ianos, a series of field surveys were launched together with rapid response through satellite imagery. We focused on two of the areas most affected by Medicane Ianos, Cephalonia island and Karditsa, Thessaly, both in Greece. A rapid landslide inventory for the Karditsa region was prepared using Copernicus Sentinel-2 satellite imagery, the first of its kind for a severe weather event in Greece. The mountainous area of Karditsa region in western Thessaly experienced the unprecedented number of 1696 landslides, mapped through satellite imagery and examined in the field. Cephalonia Island experienced a smaller number of landsides but damaging debris flows and severe structural damages. The rapid landside inventory was then compared to new methods of automated landslide mapping through change detection of satellite imagery. [ABSTRACT FROM AUTHOR]

This work investigates extreme weather events such as the onset of medicanes, which can cause severe socioeconomic impacts, along with their predictability. In order to accurately forecast such events, the Weather Research and Forecasting (WRF) model and its state-of-the-art data assimilation modeling framework (WRFDA) were set up to produce high-resolution forecasts for the case study of Medicane Ianos, which affected Greece between 17 and 19 September 2020. Information from weather stations and the satellite precipitation product IMERG was blended with the background model information from the Global Forecast System (GFS) using the 4D variational data assimilation (4D-Var) technique. New fields in an 18 km spatial resolution domain covering Europe were generated and utilized as improved initial conditions for the forecast model. Forecasts were issued based on these improved initial conditions at two nested domains of 6 km and 2 km spatial resolution, with the 2 km domain enclosing Greece. Denial experiments, where no observational data were assimilated in the initial boundary conditions, showed that the temperature fields benefited throughout the forecasting horizon from the assimilation (ranging from a 5 to 10% reduction in the average MAE values), while neutral to slightly positive (ranging from a 0.4 to 2% reduction in the average MAE values) improvement was found for wind, although not throughout the forecast horizon. The increase in spatial resolution did not significantly reduce the forecast error, but was kept at the same small order of magnitude. A tendency of the model to overpredict precipitation regardless of assimilation was observed. The assimilation of the IMERG data improved the precipitation forecasting ability up to the 18th hour of forecast. When compared to assimilation experiments that excluded IMERG data, the assimilation of IMERG data produced a better representation of the spatial distribution of the precipitation fields. [ABSTRACT FROM AUTHOR]

The limited availability of wind profile measurements has hindered atmospheric models and climate systems’ understanding. The European Space Agency’s Aeolus mission’s space-based Doppler wind lidar technology could solve this issue by measuring wind profiles in Near-Real-Time, providing valuable data for Numerical Weather Prediction (NWP) models. A case study using the COSMO NWP model demonstrates the potential of Aeolus data in improving NWP models by examining the impact of Medicane IANOS in September 2020 over the Thessaly plain. The study aims to improve our ability to predict severe weather events and advance our understanding of Earth’s atmosphere.

A forward advection scheme is incorporated in an advanced data assimilation model to provide very short-term predictions. The Local Analysis and Prediction System (LAPS) is implemented in the nowcasting mode in a case study of extreme precipitation event over Attica, Greece. The LAPS assimilated remote sensing data from satellite retrievals and XPOL radar precipitation measurements to produce objective analyses alongside their nowcasts in a forecast window up to 3 h. The results indicate that the assimilation of remote sensing data can increase the short-term precipitation predictability, with varying performance depending on the type and the combination of the assimilated remote sensing data.

The rotating-convection paradigm for tropical cyclone behaviour is shown to provide an attractive and consistent framework for interpreting the dynamics of formation and intensification of at least some medicanes. The ideas are illustrated by a case study of the medicane that formed over the eastern Mediterranean in mid-December 2020. This case study is based on analyses of data from the European Centre for Medium Range Weather Forecasts (ECMWF), imagery from the European geostationary meteorological satellite, Meteosat Second Generation, and output from a convection permitting numerical simulation of the event using the United Kingdom (UK) Met Office regional model with the RAL2 physics configuration. Limitations of the currently widely accepted interpretation of medicanes in terms of the so-called Wind-Induced Surface Heat Exchange (WISHE) intensification mechanism are discussed. [ABSTRACT FROM AUTHOR]

Mediterranean hurricanes (Medicanes) are characterized by the presence of a quasi-cloud-free calm eye, spiral-like cloud bands, and strong winds around the vortex center. Typically, they reach a tropical-like cyclone (TLC) phase characterized by an axisymmetric warm core without frontal structures. Yet, some of them are not fully symmetrical, have a shallow warm-core structure, and a weak frontal activity. Finding a clear definition and potential classification of Medicanes based on their initiation and intensification processes, understanding the role of convection, and identifying the evolution to a TLC phase are all current research topics. In this study, passive microwave (PMW) measurements and products are used to characterize warm core (WC) and deep convection (DC) for six Medicanes that occurred between 2014 and 2021. A well-established methodology for tropical cyclones, based on PMW temperature sounding channels, is used to identify the WC while PMW diagnostic tools and products (e.g., cloud-top height (CTH) and ice water path (IWP)), combined with lightning data, are used for DC detection and characterization. The application of this methodology to Medicanes highlights the possibility to describe their WC depth, intensity, and symmetry and to identify the cyclone center. We also analyze to what extent the occurrence and characteristics of the WC are related to the Medicane’s intensity and DC development. The results show that Medicanes reaching full TLC phase are associated with deep and symmetric WCs, and that asymmetric DC features in the proximity of the center, and in higher CTH and IWP values, with scarce lighting activity. Medicanes that never develop to a fully TLC structure are associated with a shallower WC, weaker and more sparse DC activity, and lower CTHs and IWP values. Ultimately, this study illustrates the potential of PMW radiometry in providing insights into dynamic and thermodynamic processes associated with Medicanes’ WC characteristics and evolution to TLCs, thus contributing to the ongoing discussion about Medicanes’ definition.

Accurate modelling of air-sea processes is essential for reliable forecasts of Mediterranean tropical-like cyclones (also known as "Medicanes"). Medicanes occasionally develop in the Mediterranean causing extreme weather conditions with catastrophic potential due to excessive precipitation, windstorms, and coastal flooding. In this work, we investigate how the complexity of ocean-wave-atmosphere coupling and model initialization affect the simulated track and intensity of the Medicane Ianos (2020). Results indicate that the model's initial conditions and the cyclone's development stage are the main drivers of track position errors, while ocean and wave feedback have a significant impact on the intensity and evolution of the cyclone. Compared with an atmosphere-only simulation, an atmosphere-ocean coupled system reproduces the cyclone's SST cooling effect (up to 3.7 °C), in agreement also with the satellite observations thus, reducing the cyclone intensity, as estimated by the minimum MSLP, the 10-m wind speed and the surface enthalpy flux. Adding a wave model to the coupled system, further increases the magnitude of ocean cooling (by about 1.2 °C), due to increased sea surface roughness leading to increased wind stress and enhanced upper ocean mixing. Overall, surface waves are shown to have competing effects on cyclone intensity i.e., negative feedback via increasing the surface momentum flux and positive feedback via increasing the enthalpy flux, the latter being more sensitive to surface roughness rather than to SST modifications brought by the wave coupled system. The turbulent air-sea fluxes under high winds, appear to be very sensitive to sea-state patterns resolved by the coupled models, highlighting the need to improve forecasting systems for extreme weather events in the Mediterranean. • Coupled ocean–wave-atmosphere model have been developed to study the Medicane Ianos. • Both wave-current and wave-atmosphere interaction processes are considered. • Coupled model reproduces the upper-ocean cooling, reducing Medicane intensity. • Medicane track forecasts are strongly depend on the cyclone's development stage. • Wave effects on sea surface roughness must be considered in Medicane forecasting. [ABSTRACT FROM AUTHOR]

On 18 September 2020, the Karditsa prefecture of Thessaly region (Greece) experienced a catastrophic flood as a consequence of the IANOS hurricane. This intense phenomenon was characterized by rainfall records ranging from 220 mm up to 530 mm, in a time interval of 15 h. Extended public infrastructure was damaged and thousands of houses and commercial properties were flooded, while four casualties were recorded. The aim of this study was to provide forensic research on a reconstruction of the flood event in the vicinity of Karditsa city. First, we performed a statistical analysis of the rainfall. Then, we used two numerical models and observed data, either captured by satellites or mined from social media, in order to simulate the event a posteriori. Specifically, a rainfall–runoff CN-unit hydrograph model was combined with a hydrodynamic model based on 2D-shallow water equations model, through the coupling of the hydrological software HEC-HMS with the hydrodynamic software HEC-RAS. Regarding the observed data, the limited available gauged records led us to use a wide spectrum of remote sensing datasets associated with rainfall, such as NASA GPM–IMREG, and numerous videos posted on social media, such as Facebook, in order to validate the extent of the flood. The overall assessment proved that the exceedance probability of the IANOS flooding event ranged from 1:400 years in the low-lying catchments, to 1:1000 years in the upstream mountainous catchments. Moreover, a good performance for the simulated flooding extent was achieved using the numerical models and by comparing their output with the remote sensing footage provided by SENTINEL satellites images, along with the georeferenced videos posted on social media. [ABSTRACT FROM AUTHOR]

Mediterranean hurricanes, or medicanes, are tropical-like cyclones forming once or twice per year over the waters of the Mediterranean Sea. These mesocyclones pose a serious threat to coastal infrastructure and lives because of their strong winds and intense rainfall. Infrasound technology has already been employed to investigate the acoustic signatures of severe weather events, and this study aims at characterizing, for the first time, the infrasound detections that can be related to medicanes. This work also contributes to infrasound source discrimination efforts in the context of the Comprehensive Nuclear-Test-Ban Treaty. We use data from the infrasound station IS48 of the International Monitoring System in Tunisia to investigate the infrasound signatures of mesocyclones using a multi-channel correlation algorithm. We discuss the detections using meteorological fields to assess the presence of stratospheric waveguides favoring propagation. We corroborate the detections by considering other datasets, such as satellite observations, a surface lightning detection network, and products mapping the simulated intensity of the swell. High- and low-frequency detections are evidenced for three medicanes at distances ranging between 250 and 1100 km from the station. Several cases of non-detection are also discussed. While deep convective systems, and mostly lightning within them, seem to be the main source of detections above 1 Hz, hotspots of swell (microbarom) related to the medicanes are evidenced between 0.1 and 0.5 Hz. In the latter case, simulations of microbarom detections are consistent with the observations. Multi-source situations are highlighted, stressing the need for more resilient detection-estimation algorithms. Cloud-to-ground lightning seems not to explain all high-frequency detections, suggesting that additional sources of electrical or dynamical origin may be at play that are related to deep convective systems.

This work investigates extreme weather events such as the onset of medicanes, which can cause severe socioeconomic impacts, along with their predictability. In order to accurately forecast such events, the Weather Research and Forecasting (WRF) model and its state-of-the-art data assimilation modeling framework (WRFDA) were set up to produce high-resolution forecasts for the case study of Medicane Ianos, which affected Greece between 17 and 19 September 2020. Information from weather stations and the satellite precipitation product IMERG was blended with the background model information from the Global Forecast System (GFS) using the 4D variational data assimilation (4D-Var) technique. New fields in an 18 km spatial resolution domain covering Europe were generated and utilized as improved initial conditions for the forecast model. Forecasts were issued based on these improved initial conditions at two nested domains of 6 km and 2 km spatial resolution, with the 2 km domain enclosing Greece. Denial experiments, where no observational data were assimilated in the initial boundary conditions, showed that the temperature fields benefited throughout the forecasting horizon from the assimilation (ranging from a 5 to 10% reduction in the average MAE values), while neutral to slightly positive (ranging from a 0.4 to 2% reduction in the average MAE values) improvement was found for wind, although not throughout the forecast horizon. The increase in spatial resolution did not significantly reduce the forecast error, but was kept at the same small order of magnitude. A tendency of the model to overpredict precipitation regardless of assimilation was observed. The assimilation of the IMERG data improved the precipitation forecasting ability up to the 18th hour of forecast. When compared to assimilation experiments that excluded IMERG data, the assimilation of IMERG data produced a better representation of the spatial distribution of the precipitation fields.

The present work analyzes the synoptic, thermodynamic, and microphysics characteristics of two Mediterranean cyclones that occurred in February–March 2023. The analysis is mainly carried out through the use of passive microwave (PMW) satellite measurements, which allow us to follow the cyclones' evolution and state whether Helios and Juliette can be considered as Mediterranean tropical-like cyclones (i.e., medicanes). Both cyclones show a very similar evolution, with a low-stratospheric warm air anomaly during the development phase, followed by the development of a warm anomaly in the low−/mid-troposphere. This feature is often observed in medicanes (e.g., Qendresa, Zorbas), except for few cases (i.e., Medicane Ianos, which shows a warm core (WC) development clearly driven by diabatic processes without a preliminary warming signal in the lower stratosphere and upper troposphere). The analysis carried out highlights that, while Helios maintains this setting through its whole lifetime, Juliette undergoes tropical transition in the final stage of its evolution. As opposed to most medicane cases, the PMW precipitation microphysics diagnostics shows the predominance of shallow clouds, with almost total absence of ice hydrometeors and deep convection in the proximity of the WC center (i.e., within 100 km radius) for Helios and during the initial stage of Juliette. PMW radiometry provides strong indication that diabatic heating plays a role in the WC development when the onset of deep convection features is identified in the proximity of the Juliette cyclone center. Moreover, the PMW cloud-top height product does not show a closed cloud-free eye for Helios, while it is observed for the final stage of Juliette as often happens during medicanes' mature phase. Therefore, we deem that while Helios can be labeled as a warm seclusion, Juliette can be included in the tropical-like cyclone category. • Helios and Juliette originate from similar thermodynamic and synoptic conditions. • A warm core originating from diabatic processes develops in Juliette at a later stage. • Deep convection features close to the center are never found in Helios. • Juliette shows deep convection within the warm core region. • Helios is a warm seclusion; Juliette is classified as a tropical-like cyclone. [ABSTRACT FROM AUTHOR]

On 18 September 2020, the Karditsa prefecture of Thessaly region (Greece) experienced a catastrophic flood as a consequence of the IANOS hurricane. This intense phenomenon was characterized by rainfall records ranging from 220 mm up to 530 mm, in a time interval of 15 h. Extended public infrastructure was damaged and thousands of houses and commercial properties were flooded, while four casualties were recorded. The aim of this study was to provide forensic research on a reconstruction of the flood event in the vicinity of Karditsa city. First, we performed a statistical analysis of the rainfall. Then, we used two numerical models and observed data, either captured by satellites or mined from social media, in order to simulate the event a posteriori. Specifically, a rainfall–runoff CN-unit hydrograph model was combined with a hydrodynamic model based on 2D-shallow water equations model, through the coupling of the hydrological software HEC-HMS with the hydrodynamic software HEC-RAS. Regarding the observed data, the limited available gauged records led us to use a wide spectrum of remote sensing datasets associated with rainfall, such as NASA GPM–IMREG, and numerous videos posted on social media, such as Facebook, in order to validate the extent of the flood. The overall assessment proved that the exceedance probability of the IANOS flooding event ranged from 1:400 years in the low-lying catchments, to 1:1000 years in the upstream mountainous catchments. Moreover, a good performance for the simulated flooding extent was achieved using the numerical models and by comparing their output with the remote sensing footage provided by SENTINEL satellites images, along with the georeferenced videos posted on social media.

There has been in recent years an increase in interest and concerns about natural disasters, both in the scientific community and the society, in relation to their frequency and intensity, the association to global warming, and cyclones (hurricanes and medicanes). In this work, two environmental hydrodynamics models are presented. The first model is built for Hurricane Irma that took place in 2017 in the Caribbean and the second for medicane Zorba that took place in 2018 in the Mediterranean Sea. The models were developed using downscaling techniques on the MOHID platform (a free open model developed for hydrodynamic solution). Water surface currents results are presented for regions of interest together with water level variations in Virtual Maregraphic Stations, “Isabella de Sagua” at Sagua de la Grande in Cuba, Key West in USA, Katacolon and “Kalamai” in Greece, all of them located in the trajectory of both cyclones. Promising results on the modeling of the interaction between water and the atmosphere aligned with available open-source data demonstrate the accuracy of inverse problem-based solutions for natural disaster modeling and its potential for drift simulation of floating objects in future studies. [ABSTRACT FROM AUTHOR]

Abstract The link between hurricanes or typhoons and their generated ambient noise has recently become a frontier topic in the field of applied seismology. In the Mediterranean region, infrequent tropical-like cyclones, known as Medicanes or Mediterranean hurricanes, with similar characteristics with hurricanes appear, with the most recent storm occurred on September 27–30, 2018 in South Greece, which characterized by gale winds, severe precipitation, and a low pressure center, accompanied with a spiral pattern of thunderstorms. In this work, we describe the Medicane's induced ambient seismic noise fluctuations, as recorded in seismological station along to the path of the recent Medicane, in terms of non-extensive statistical physics. We found that the Medicane's induced ambient seismic noise increments follow the q-Gaussian distribution. This indicates that Medicane induced ambient seismic noise's fluctuations are not random and present long-term memory effects that could be described in terms of Tsallis entropy. Our results suggest that in the Medicane system that affected the Southwest Peloponnese the q –values of the induced ambient seismic noise's fluctuations in the Kalamata (KLMT) seismological station located in Southwest Peloponnese are q ≈ 1. 67 , which corresponds to n=2 degrees of freedom system, indicating that Medicane induced ambient seismic noise fluctuations compose of two independent Gaussian random variables. For stations as that of APE (Apiranthos, Naxos island, Cyclades), where an attenuated Medicane was observed, a q ≈ 1.57 obtained, which is similar with that observed in the KNDR (Koundoura, South West Crete) seismological station, where the Medicane appears before its main organization as intensively observed in the KLMT station. For the CHAN (Chania, West Crete) station a q ≈ 1.32 was observed which corresponds to about 5 degrees of freedom indicating that Medicane induced ambient seismic noise fluctuations compose of about five independent Gaussian random variables, in agreement with the week intensity of Medicane observed in Chania. Highlights • Study of Medicane induced ambient seismic noise apparent fluctuations. • Medicane seismic noise fluctuations described by a q-Gaussian distribution. • Medicane induced seismic noise's fluctuations present long-term correlation. [ABSTRACT FROM AUTHOR]

The adverse and rapidly changing weather conditions during a Mediterranean cyclone (medicane) pose a serious threat to maritime navigation in general. Additionally, failure in correction for GNSS signal tropospheric delay was supposed to significantly degrade the quality of GNSS-based position estimation. Here we present the study results aimed at determination of GPS positioning performance quality and GPS tropospheric error based on experimental observation during the November 2017 medicane. We found identifiable degradation of GPS positioning performance due to medicane-caused tropospheric delay, and propose corrective actions aimed at maintaining GPS positioning performance resilience for several classes of GNSS maritime applications. [ABSTRACT FROM AUTHOR]

This study investigates an intense tropical-like cyclone which formed south of Sicily on 7 November 2014 and affected the central Mediterranean. The cyclone made landfall at Malta and eastern Sicily. The sustained surface wind speed reached 23.7 m/s (named tropical cyclone strength) at Lampedusa island, while a minimum mean sea-level pressure of 984 hPa was recorded at Malta. Baroclinic instability appeared to be important for its formation since it took place in a region with deep convection and was associated with a pre-existing low-level depression, a baroclinic zone and a dynamic tropopause anomaly. Phase space diagrams determined objectively the symmetry and the warm core structure of the system. The medicane was simulated by the non-hydrostatic WRF-ARW numerical weather prediction model. The role of the sea surface temperatures (SSTs) on the development of the medicane was investigated through numerical experiments in which climatological SSTs and uniform warm and cold SST anomalies were imposed. The motivation for such experiments has been provided by the occurrence of warm SST anomalies along its track. A strong medicane, with shorter lifetime, would have developed over the central Mediterranean Sea even if the SSTs were near the normal conditions of November. [ABSTRACT FROM AUTHOR]

The Mediterranean basin occasionally hosts tropical‐like cyclones named “Medicanes”. Medicanes may have intensity comparable to hurricanes in terms of wind speeds along with an axisymmetric cloud structure. Although these events can be particularly violent, very few studies so far have investigated the distribution and temporal evolution of deep convection within these cyclones. In this study, the characteristics and lifetime of deep convection and lightning activity surrounding the core of the longest‐lasting and probably the most intense Medicane ever recorded in terms of wind speed (Rolf, November 2011) are presented by all available means of microwave and infrared satellite retrievals and a lightning detection system. Results showed that deep convective clouds penetrated the lowest stratosphere and were wrapped around the cyclone centre during the intensification period. Lightning activity was mostly active about a day before the maximum strength of the cyclone studied and it was not temporarily correlated with the most intense deep convection activity. Overall, this study reveals that spatial and temporal distribution of deep convection and lightning activity around the centre of Rolf show more similarities with Tropical Cyclones than intense Mediterranean cyclones. [ABSTRACT FROM AUTHOR]

Mediterranean cyclones with tropical‐like characteristics such as spiral cloud coverage and a central cloud‐free “eye” are referred to as medicanes. These systems have been analyzed due to their relation with high‐impact weather. In previous studies, the identification of medicanes has been typically performed subjectively, using satellite pictures, but also objectively through three‐dimensional diagnosis of a warm core and an axisymmetric structure. Despite the presence of these characteristics, it is still unclear if medicanes show dynamical similarities with tropical cyclones. We analyse the (thermo‐)dynamics of a recognized medicane that occurred in December 2005 by applying different diagnostics to a high‐resolution simulation. These diagnostics are focused on the intensification, dynamical structure and water budget of this representative case, aiming to highlight extratropical and tropical cyclone characteristics. Three stages in the medicane life cycle are identified. In stage I, a potential vorticity (PV) streamer reaches the Mediterranean, triggering deep convection and deepening the medicane's central surface pressure due to diabatic heating. When the lowest central pressure is reached (stage II), the medicane presents a warm core and an axisymmetric structure. However, convection is rather weak and the PV streamer evolves into a cut‐off system which contributes to the deepening of the medicane's surface pressure. Finally, stage III corresponds to the decay phase where the medicane tends to weaken and lose its axisymmetric structure. Our results highlight the detrimental role of deep convection prior to the mature stage of the medicane, as well as the possibility of positive or negative feedback of upper‐tropospheric dynamics on the central surface pressure. In addition, we show that the medicane warm core might be achieved due to front seclusion, while the “eye” formation is associated with dry air intrusions. Our analysis suggests that medicanes are hybrid systems combining characteristics of both tropical and extratropical cyclones and thus they plausibly correspond to subtropical cyclones. [ABSTRACT FROM AUTHOR]

Tropical-like Mediterranean cyclones (medicanes) have been documented and investigated in the literature, revealing that their physical mechanisms are still poorly understood and likely not unique across cases. During late hours of 7 November 2014 a small-scale cyclone was detected over the Sicilian channel, affecting the Islands of Lampedusa, Pantelleria and Malta. Gust wind values exceeding 42.7 m s − 1 and a pressure drop above 20 hPa in 6 h were registered in Malta. Clear signatures of a well-defined cloud-free eye surrounded with convective activity of axisymmetric character were identifiable through IR satellite imagery during the late stages of the cyclone, resembling the properties of a hurricane. We investigate the cyclogenesis and posterior development of this small-scale cyclone as well as its physical nature; to this aim, a set of high-resolution sensitivity numerical experiments were performed. Hart's phase diagrams adapted to the Mediterranean region clearly reveal the tropical characteristics of the simulated storm. A numerical sensitivity analysis by means of a factor separation technique is used to gain quantitative insight on the roles latent heat release, surface heat fluxes and upper-level PV signatures (dynamically isolated through a PV-Inversion technique) have on the unfold of this singular event. Results show the importance of the upper-level dynamics to generate a baroclinic environment prone to surface cyclogenesis and in supporting the posterior tropicalization of the system. On the contrary, latent heat release and surface heat fluxes factors do not seem to contribute, as individual processes, to the genesis of the cyclone as much as it could be suspected, considering it behaves as a tropical-like cyclone. However, the asynchronous synergism between latent heat release and PV factors plays a crucial role for the intensification of the cyclone towards reaching the pure diabatic phase. [ABSTRACT FROM AUTHOR]

The accurate prediction of Mediterranean tropical-like cyclones, or medicanes, is an important challenge for numerical weather prediction models due to their significant adverse impact on the environment, life, and property. The aim of this study is to investigate the sensitivity of an intense medicane, which formed south of Sicily on 7 November 2014, to the microphysical, cumulus, and boundary/surface layer schemes. The non-hydrostatic Weather Research and Forecasting model (version 3.7.1) is employed. A symmetric cyclone with a deep warm core, corresponding to a medicane, develops in all of the experiments, except for the one with the Thompson microphysics. There is a significant sensitivity of different aspects of the simulated medicane to the physical parameterizations. Its intensity is mainly influenced by the boundary/surface layer scheme, while its track is mainly influenced by the representation of cumulus convection, and its duration is mainly influenced by microphysical parameterization. The modification of the drag coefficient and the roughness lengths of heat and moisture seems to improve its intensity, track, and duration. The parameterization of shallow convection, with explicitly resolved deep convection, results in a weaker medicane with a shorter lifetime. An optimum combination of physical parameterizations in order to simulate all of the characteristics of the medicane does not seem to exist.

[Display omitted] • Two earthquakes, a flood and a medicane occurred amid the COVID-19 pandemic in Greece. • The study is based on daily recorded laboratory-confirmed COVID-19 cases. • Only the medicane increased the daily COVID-19 cases during the selected post-disaster period. • Post-disaster decrease or stability of the COVID-19 cases have been also detected. • Pandemic and disasters features and response actions affected the cases evolution. Since the first confirmed COVID-19 case in December 2019 the pandemic has severely affected humanity in various ways on all sectors of the everyday life. Natural hazards and related disasters did not stop for the novel virus. The parallel evolution of disasters and the pandemic have high potential for producing compound emergencies characterized by new unprecedented challenges. Greece was no exception. It was struck by disasters induced by geological and hydrometeorological hazards amid the pandemic. The most destructive events in terms of human and economic losses were the Mw = 5.7 Epirus and Mw = 6.9 Samos earthquakes on March 21 and October 30 respectively, the Evia flood on August 9 and the Ianos medicane in mid-September 2020. We studied the daily recorded laboratory confirmed COVID-19 cases in the disaster-affected areas in selected pre- and post- disaster periods. Increase of the reported COVID-19 cases in the post-disaster period has been detected only after the Ianos medicane in affected areas. No change in cases was observed after the studied earthquakes and flood. We examined various factors related to the evolving pandemic, the studied disasters and their management plan that may have contributed to the post-disaster evolution of cases. It is shown that the preexisting viral load and the infection rate in the affected areas, the intensity of the disaster effects and the measures adopted for the effective disaster management of the compound emergencies have the potential to affect the post-disaster evolution of the pandemic in the disaster affected areas. [ABSTRACT FROM AUTHOR]

Understanding the governing mechanisms of atmosphere–wave–ocean​ interactions is critical for unravelling the formation and evolution mechanisms of severe weather phenomena. This study aims at investigating the effects of atmosphere–wave–ocean​ feedbacks on a Mediterranean tropical-like cyclone (medicane), occurred on 27–30 September 2018 at the central-eastern Mediterranean Sea and characterized by severe environmental and socioeconomic impact. To unveil the interactions across the air–sea interface, the medicane was simulated by an integrated modelling system consisting of the Chemical Hydrological Atmospheric Ocean wave System (CHAOS), upgraded by embedding to it the Nucleus for European Modelling of the Ocean (NEMO) as ocean circulation component. Coupled simulations revealed that air–seaheat transfer and Ekman pumping, bringing sub-surface cold waters in upper ocean layers (upwelling), caused SST cooling (∼ 2–3 °C). SST cooling triggered a negative feedback loop procedure tending to balance between atmospheric and ocean processes. It also attenuated the cyclone and, subsequently, reduced the atmospheric energy embedded in ocean through the upper ocean vertical stratification weakening, thus, upper ocean vertical mixing, upwelling and SST cooling. The waves adjusted this feedback loop making the system more resistant in air–sea flux variations. Waves additionally weakened the cyclone not only due to the kinetic energy loss in the lower-atmosphere but also due to the enhancement of SST cooling which is attributed to the strengthening of Ekman pumping and vertical mixing, forced by wind stress increase. Nevertheless, waves partially balanced the air–wave–sea exchanges through the slight enthalpy flux gain under high wind conditions which is explained by considering the increase of enthalpy transfer coefficient in rougher sea areas. • A case study of a Mediterranean tropical-like cyclone also known as medicane. • CHAOS has been upgraded to include NEMO model as ocean circulation component. • CHAOS reproduces the cooling of the upper ocean along the track of the cyclone. • The cyclone's wind stress induces Ekman pumping at the area of interest. • Ocean waves enhance air-sea momentum flux, Ekman pumping, and upper-ocean cooling. [ABSTRACT FROM AUTHOR]

Over the last few years, several authors have presented contrasting models to describe the response of boulders to extreme waves, but the absence of direct observation of movements has hindered the evaluation of these models. The recent development of online video-sharing platforms in coastal settings has provided the opportunity to monitor the evolution of rocky coastlines during storm events. In September 2018, a surveillance camera of the Marine Protected Area of Plemmirio recorded the movement of several boulders along the coast of Maddalena Peninsula (Siracusa, Southeastern Sicily) during the landfall of the Mediterranean tropical-like cyclone (Medicane) Zorbas. Unmanned autonomous vehicle (UAV) photogrammetric and terrestrial laser scanner (TLS) surveys were performed to reconstruct immersive virtual scenarios to geometrically analyze the boulder displacements recorded in the video. Analyses highlighted that the displacements occurred when the boulders were submerged as a result of the impact of multiple small waves rather than due to a single large wave. Comparison between flow velocities obtained by videos and calculated through relationships showed a strong overestimation of the models, suggesting that values of flow density and lift coefficient used in literature are underestimated. [ABSTRACT FROM AUTHOR]