the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 20 Aug 2025
Environmental Characteristics Associated with the Tropical Transition of Mediterranean Cyclones
Abstract. Cyclonic perturbations in the Mediterranean region sometimes acquire characteristics typical of tropical cyclones, such as a deep inner warm core. In these cases, they become very intense structures that can cause large precipitations and significant damage. In this study, the environmental conditions during the intensification of cyclones are investigated using reanalysis data. A comparison of the conditions associated with the evolution of classical and intense cold-core extratropical cyclones and those associated with the development of tropical-like disturbances highlights the characteristic that favors the conversion: a much larger potential intensity and a weaker vertical wind shear. The larger potential intensity associated with Mediterranean tropical-like cyclones comes from both higher SST and a strong PV-intrusion that destabilizes the air column. Sea surface cooling induced by the cyclones is further shown to play a role in the dissipation of tropical-like cyclones. Future research should focus on the role of potential intensity as a precursor for Mediterranean tropical-like cyclone forecasting, improving predictive capabilities and risk mitigation strategies in the Mediterranean region.
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RC1: 'Comment on egusphere-2025-3861', Anonymous Referee #1, 28 Aug 2025
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The paper classifies Mediterranean cyclones into three categories and describes the mean and standard deviation of their characteristics 36 hours before their maximum intensity. The paper sorely lacks arguments to convince the reader that the three categories of cyclones have consistent characteristics and that the framework around the maximum intensity is relevant for analyzing such a diversity of cyclones.
Major comments
The title "Environmental Characteristics Associated with the Tropical Transition of Mediterranean Cyclones" is misleading. The paper compares ETC, intense ETC and MLTC over a 72-h period centered on the first minimum sea level pressure (SLP). It therefore deals with the intensification of the three types of cyclones, not the tropical transition of Mediterranean cyclones.
With regard to tropical transition (TT), the authors should refer to cyclones for which "a fundamental dynamic and thermodynamic transformation of an extratropical precursor (of baroclinic origin and initially considered a cold-core system) is required to create a warm-core tropical cyclone" (Davis and Bosart 2004). In other words, TT deals with ETCs that transform into MLTCs. These transformed cyclones correspond to your definition of hybrid cyclones, which are not included in the study. Under these conditions, I do not understand how the study can actually address TT.
Line 26, it should of interest to cite Miglietta et al. (2025) "A medicane is a mesoscale cyclone that develops over the Mediterranean Sea and displays tropical-like cyclone characteristics: a warm core extending into the upper troposphere, an eye-like feature in its center with spiral cloud bands around, an almost windless center surrounded by nearly-symmetric sea-surface wind circulation with maximum wind speed within a few tens of km from the center."
Line 95, Mediterranean Tropical-Like Cyclones (MTLC) ("also known as Medicanes", Line 19), are defined as cyclones that during part of their lifetime develop a deep warm core for at least six hours while they are over the sea. This corresponds to the first criterion in the definition by Miglietta et al. (2025). The other criteria are therefore discarded. This could partly explain the difference in the number of occurrence reported in Section 3.1, i.e. about 1.5 Medicanes per year compared to 3.4 cyclones per year of MLTC. It also means that the MLTC you have defined are not Medicanes. They should therefore be named "Deep Warm-Core Cyclones (DWCD)."
Section 2.2. The use of a different radius to calculate the B and V parameters (100 km versus 125 km) must be justified. Furthermore, these radii are well below 200 km, as used by Chaboureau et al. (2012), or 250 km, as used by Fita and Flaounas (2018). The use of a small radius must also be justified. As noted by Miglietta et al. (2025), these small radii "may be misleading for the diagnosis of symmetric or upper warm-core structures. These considerations need to be taken into account in future studies."
Section 3.1. The threshold of 20% chosen for the classification of intense ETC must be justified. In addition, this section (or the next one) should include a description of the distribution of SLP and track length for the three categories.
Figure 1, line 144, "About one-third of MTLC have a full warm core at the time of peak intensity." In other words, about two-thirds of MTLC do not have a full warm core at the time of peak intensity, meaning that they are not MTLC at that moment. This shows that the time of peak intensity is not the TT time for two third of the MLTC. This implies a broad TT spectrum for the MLTC set.
In most figures, the mean and standard deviation of several variables are shown. This suggests that these variables have a Gaussian distribution, which is certainly not the case. Instead, the median and interquartile values should be shown. The 5th and 95th percentiles and outliers should also be added to the lower panels of Figures 4, 5, 6, 9, 10, 13 and A5.
References
Chaboureau, J.-P., F. Pantillon, D. Lambert, E. Richard, E. and C. Claud, 2012: Tropical transition of a Mediterranean storm by jet crossing. Quart. J. Roy. Meteor. Soc., 138, 596–611, https://doi.org/10.1002/qj.960
Davis, C. A., and L. F. Bosart, 2004: The TT problem: Forecasting the tropical transition of cyclones. Bull. Amer. Meteor. Soc., 85, 1657–1662, https://doi.org/10.1175/BAMS-85-11-1657
Fita, L., and E. Flaounas, 2018: Medicanes as subtropical cyclones: The December 2005 case from the perspective of surface pressure tendency diagnostics and atmospheric water budget. Quart. J. Royal Meteor. Soc., 144, 1028–1044. https://doi.org/10.1002/qj.3273
Miglietta, M. M., and Coauthors, 2025: Defining Medicanes: Bridging the Knowledge Gap Between Tropical and Extratropical Cyclones in the Mediterranean. Bull. Amer. Meteor. Soc., in press, https://doi.org/10.1175/BAMS-D-24-0289.1
Citation: https://doi.org/10.5194/egusphere-2025-3861-RC1
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