Analysis of a Mediterranean Tropical-Like Cyclone. Sensitivity to WRF Parameterizations and Horizontal Resolution

Due to their rarity and intensity, Mediterranean Tropical-Like Cyclones (TLCs; also known as medicanes) have been a subject of study over the last decades and lately the interest has undoubtedly grown. The current study investigates a well-documented TLC event crossed south Sicily on November 7–8, 2014 and the added value of higher spatial horizontal resolution through a physics parameterization sensitivity analysis. For this purpose, Weather Research and Forecasting model (version 3.9) is used to dynamically downscale ECMWF Re-Analysis (version 5) (ERA5) reanalysis 31 km spatial resolution to 16 km and 4 km, as parent and inner domain, respectively. In order to increase the variability and disparity of the results, spectral nudging was implemented on both domains and the outputs were compared against satellite observations and ground-based stations. Although, the study produces mixed results, there is a clear indication that the increase of resolution benefits specific aspects of the cyclone, while it deteriorates others, based on both ground and upper air analyses. The sensitivity of the parent domain displays an overall weak variability while the simulations demonstrate a positive time-lag predicting a less symmetric cyclone with weak warm core. On the contrary, inner domain analysis shows stronger variability between the model simulations reproducing more distinct clear tropical characteristics with less delayed TLC development for most of the experiments.