How much do Mediterranean tropical-like cyclones (Medicanes) rely on diabatic heating?

<p>Some mesoscale cyclones in the Mediterranean attain tropical-like characteristics, such as a deep warm core, absence of fronts, and a cloud-free “eye”. Some others have less symmetry, a shallow warm core structure, and a weak frontal activity, but both categories of cyclones are so-called “Medicanes”. Due to the vast variety of features that resemble tropical cyclones, polar lows and extratropical cyclones, Medicanes still do not have an official definition. The rapid intensity changes and tropical transitions of Medicanes, the evolution of associated deep convection, and the large spread of forecast tracks in numerical weather prediction models, as well as scarce in-situ observations highlight the challenges in understanding the dynamics of these weather systems.</p> <p>In this study, we try to improve our understanding of the atmospheric ingredients that build Medicanes, and most importantly, how much contribution does diabatic heating has on Medicanes’ intensification process. To achieve this, numerical diagnostics are used to explain the evolution and contribution of diabatic processes in case studies of Medicanes observed between 2005 and 2021. The WRF model is utilized in high-resolution mode, and its results are evaluated against satellite and surface observations in order to filter out the problematic simulations. Then, the Pressure Tendency Equation (PTE) is applied, which helps to decompose the contribution of dynamic atmospheric components in each stage of a Medicane’s lifetime. Results show that the contribution of diabatic processes and large-scale forcing varies considerably among the studied Medicanes. Moreover, an online Potential Vorticity (PV) tracer module in WRF provides an additional metric for the role of latent heating during the same Medicanes. Both approaches help to identify important differences among the case studies and shed a new light on a new pathway of Medicane development that was previously ignored.</p>