NEW PERSPECTIVES AND ADVANCEMENTS IN MICROWAVE-BASED ANALYSES AND CHARACTERIZATION OF MEDICANES

L. P. D’Adderio¹, S. Sebastianelli¹, D. D’Armiento¹, D. Casella¹, P. Sanò¹, D. Herndon², C. Sarran³, G. Panegrossi¹

¹National Research Council of Italy, Institute of Atmospheric Sciences and Climate (CNR-ISAC), Rome, Italy, ²Cooperative Institute for Meteorological Satellite Studies (CIMSS), University of Wisconsin-Madison, Madison, WI, USA, ³Princeton University, Princeton, NJ, USA

Medicanes (Mediterraean Hurricane) are meteorological events with the potential to cause devastating floods, storm surges and windstorms, often leading to significant disruption and casualties. During their mature phase, they exhibit phenomenological features typical of tropical (or sub-tropical) cyclones, such as a warm core (WC), a cloud free eye surrounded by spiraling rain bands around the center, a closed vortex associated to strong near-surface winds, and heavy precipitation. Generally, these cyclones originate from extra-tropical cyclones showing a cut-off from the main flow allowing the intrusion of relatively warm stratospheric air resulting in a top-bottom WC development. More rarely, they undergo the so-called tropical-like cyclone (TLC) transition during their mature phase, exhibiting at some point a deep axi-symmetric WC of diabatic origin (i.e., sustained by the latent heat release due to air-sea interaction), and deep convection (DC) in proximity of the center (that also trigger the latent heat release). The term Medicane generally refers to both types of cyclones regardless of the thermodynamical and microphysical processes originating them.

The present work provides an overview of recent studies on the use of satellite observations to monitor and to characterize the WC, the DC, the presence of a closed eye surrounded by a ring-shaped band of intense winds during the cyclone evolution, and to identify the TLC transition. Relevant advances on this topic are being accomplished within the ESA project “Earth Observations as a cornerstone to the understanding and prediction of tropical-like cyclone risk in the Mediterranean (MEDICANES)”. The detection and characterization of WC and DC are based on satellite passive microwave (PMW) measurements from different radiometers onboard Low Earth Orbit (LEO) satellites. In particular, temperature sounding channels in the 50-60 GHz oxygen absorption band are used to identify the presence of the WC, while high frequency channels (from 88 GHz for higher resolution imagers up to 183 GHz even for sounder radiometers) are used to identify the presence of the closed eye and the DC areas. On the other hand, near-surface ocean wind vectors derived from scatterometer measurements (ASCAT onboard MetOp satellites and WindRAD onboard Feng Yun satellites) are used to monitor the evolution of the surface wind field as the cyclone evolves from the development to the mature stage. In particular, in analogy with what is done for tropical cyclones, the characterization in terms of radius of maximum wind (RMW) can be used as a proxy to identify the cyclone’s intensification. The techniques and the methodologies originally developed for tropical cyclones, have been tuned for the Mediterranean cyclones (e.g., medicanes are weaker, smaller in size and have shorter life time than tropical cyclones, and this can reflect in different channels or variables to be used). An additional step forward in medicanes’ characterization and monitoring is being carried out exploiting different machine learning (ML) approaches for automated detection of the Medicanes’ features, including the identification of the WC. New developments and applications of the satellite-based methodologies developed within the ESA MEDICANES on a large dataset of medicanes cases occurred between year 2000 and 2023 will be shown.