Effect of a positive Sea Surface Temperature anomaly on a Mediterranean tornadic supercell

Mario Marcello Miglietta,Vincenzo Motola,Jordi Mazon,Antonello Pasini

doi:10.1038/s41598-017-13170-0

Abstract

Extreme events represent a topic of paramount importance and a challenge for modelling investigations. Due to the need of high-resolution models, the study of severe localized convective phenomena is even more critical, especially in relation to changes in forcing factors, such as sea surface temperatures (SSTs), in future climate scenarios. Here, we analyze the effect of changes in SSTs on the intensity of a tornadic supercell in the Mediterranean through modelling investigations. We show dramatic (nonlinear) changes for updraft helicity and vertical velocity, which measure the intensity of the supercell, even for variations of SST only of + /−1 K.

Highlights

The Mediterranean basin is regularly affected by severe convective events, often of limited predictability[4], which are frequently related to the cyclone activity in the region[5,6]
The radar reflectivity images[32] suggest that the orography south-southwest of Taranto played a key role in the development of the supercell: a line of convective cells was triggered by Sila mountains, moved downstream and approached the coast near Taranto[31,32]
Due to the critical impacts of extreme events on territories, ecosystems and humans, a strong interest for their attribution has raised in order to understand how much the changes in their features can be due to the anthropogenic factors manifested in the climate change

Summary

Introduction

The Mediterranean basin is regularly affected by severe convective events, often of limited predictability[4], which are frequently related to the cyclone activity in the region[5,6]. The issue is interesting from a climate change perspective, considering the predicted increase of SST in several basins and the intrinsic difficulties of determining the changes in intensity, frequency, and location of tornadoes and supercells in future climate scenarios Such difficulties depend on the very high resolution required for their proper representation, which is far from that available in the current climate simulations[19], and on the www.nature.com/scientificreports/. At present, the best one can do is to analyze the change in the parameters favorable to severe convection, obtained from downscaled high-resolution simulations nested into global circulation model projections This category of studies has generally predicted an increase in the frequency of these events in future scenarios, associated with greater potential instability that offsets the predicted reduction in deep-layer shear, resulting in environments more favorable for severe thunderstorms[20,21,22,23]

Methods

Results

Conclusion