Case study of Medicane Ianos: Investigation into its triggering mechanism

The aim of this work  is to study the triggering mechanism and the other  factors involved in the development of the Medicane ‘Ianos’ over the Ionian Sea, occurred during 15-20 September 2020. Ianos was one of the most intense Tropical-Like cyclones(TLC) observed on the Mediterranean.  It was characterized by a minimum pressure of 984 hPa and generated winds of over 120 km/h and up to 5 meters of significant waves height.  It also caused massive flooding along the Greek coast and rain accumulations of more than 500 mm in inland areas. The triggering and the physical process for intensifying  the cyclone has been studied using satellite and the convection permitting numerical simulation at 1 km resolution. Factors such as dry air intrusion due to the stratosphere-troposphere exchange partially helped in the formation and stabilization of the eye of the cyclone.  Moreover, convection was initially triggered by the cold north-easterly advection that de-stabilized the atmosphere in Gulf of Sidra, helping in the deep convection and rainfall in the region during 15 September. Further, the formation of the low pressure system in Libya that later interacted with this convective system along with the dry air intrusion led to the formation of the cyclone. The latent heat release mostly sustains and intensified the storm processes. This can also be deduced (in conjunction with the marine phenomena of mixing, waves, etc.) from the decrease in Sea Surface Temperature along the TLC track. Understanding the mechanism of the storm initiation process is an important task for improving the forecast in the future in order to improve forecasts but also to limit the impacts of these extreme phenomena, in a complex context of climate change.