Diagnostics-based evaluation of Mediterranean extreme convective storms on high-resolution simulations under Destination Earth initiative

The Destination Earth (DestinE) is a flagship initiative of the European Commission to develop a highly accurate digital model of the Earth on a global scale. This model will monitor, simulate and predict the interaction between natural phenomena and human activities. DestinE will unlock the potential of digital modelling of the Earth system at a level that represents a real breakthrough in terms of accuracy, local detail, access-to-information speed and interactivity.

The initial focus will be on the effects and prediction of climate change and extreme weather events, their socio-economic impact and possible adaptation and mitigation strategies. One of the subcomponents of DestinE is the On-Demand Extremes digital twin (DestinE_330), which will build a configurable framework for impact assessment and prediction of weather-induced extremes at sub-kilometre scales.

Within the framework of this initiative and from diagnostics point of view, here we evaluate initial simulations of both the global (~4 km) and the regional weather-induced (~500 km) DestinE prototype components for the representation of high-impact and extreme convective weather over the Mediterranean region, with two specific problems which are highly sensible to increasing resolution and which anthropogenic climate change could worsen: A very high-impact static convective storm formed in front of Valencia (Spain) and a rare tropical-like convectively-driven cyclone (Medicane Ianos) over the Ionian Sea.

The storm in Valencia, probably a mesoscale convective system, produced heavy precipitation (>100 mm in 2 hours) and reported the largest accumulation for one day in May for Valencia. The socioeconomic impact was also severe. This event had very low predictability in high-resolution convection-allowing models, being a challenge from a numerical modelling point of view. None of the national operational models nor global models over the region showed signals of convective activity with such features in the east of Spain.

Ianos was a extremely rare Mediterranean tropical-like cyclone, behaving as a hurricane, that impacted the eastern Mediterranean on 17 and 18 September 2020, especially Greece, leaving severe damage with heavy rains (peak of >600 mm) and strong winds (peak of 195 km/h) and fatalities. Operational forecasts of this event were not highly valuable, thus it a another highly recommended case study.