Researchers at the European Center for Medium-Range Weather Forecasts and TU Freiberg have developed a framework to better predict extreme precipitation events in Mediterranean countries.
Heavy rainfall has disastrous consequences for societies and economies. Locations around the Mediterranean are frequently affected by such events, leading to landslides and floods. “However, it is extremely difficult to predict exactly when and where heavy rain will occur several days in advance. Consequently, researchers are striving to develop new tools to better predict extreme weather events allowing early warnings and appropriate mitigation strategies,” explains first author Nikolaus Mastrantonas, who conducted Study as a PhD student within the CAFE funded research project.
Learning from the past to shed light on the future
The researchers analyzed weather data from 1979 to today, and grouped daily weather into nine distinct meteorological patterns over the Mediterranean. The study shows that there is a strong relationship between these nine patterns and the location of the extreme weather event. “We can now use the data to come up with a model that helps better predict heavy rains in the Mediterranean,” says Professor Joerg Machulat of TU Bergakademie Freiberg. PhD is supervised by geo-ecologist Nikolaus Mastrantonas and adds: “When it comes to climate, the Mediterranean is a particularly interesting region surrounded by large continents and mountain ranges. The regional climate of the region is also dependent on broad patterns over the Atlantic and the Balkans. And the Black Sea. “
Mountains create links across remote sites
According to the study, the nine patterns are associated with unstable low pressure systems such as low plots and a low basin, or stable anticyclone conditions, such as hills, that extend for hundreds of kilometers. “Such conditions lead to extreme precipitation events in different sub-regions of the Mediterranean,” says Nikolaos Mastrantonas. To name one example: a low pressure system centered over the Bay of Biscay increases the likelihood of heavy rainfall over the mountainous and coastal regions of Spain, Morocco, Italy, and even in the Western Balkans by more than six times.
The team also found that the mountains create a strong link between remote regions. In central-western Italy, for example, three out of ten extreme cases occur simultaneously with extremism in Montenegro and Croatia, even though roughly 500 kilometers lie between these two regions. “This is the result of the Apennine Mountains blocking a large part of the airflow, and the humidity often forces to accelerate in the western part of Italy, and on the same day over Croatia,” explains the young researcher.
New information helps forecast models further develop
According to the scientists, current weather forecast models can already provide reliable information about weather fluctuations over a wide range up to three weeks in advance, a time frame known as the seasonal subdomain. “As a next step in this work, we will determine the reliability of the latest weather prediction models in forecasting the nine identified patterns. Professor Jörg Machulat explains that our aim is to incorporate such information into new forecast products to report severe weather over the Mediterranean at semi-seasonal levels. .
Background: The CAFE Research Project
CAFE, Advanced Climate Prediction for Semi-seasonal Extreme Events, (http: // www.
Original publication: Nicolaus Mastrantonas, Pedro Herrera Lormendes, Linus Magnuson, Florian Papenberger, Jörg Machulat: Extreme precipitation events in the Mediterranean: spatiotemporal characteristics and the connection to large-scale air flow patterns, International Journal of Climatology. https: /
Professor D. Jörg Machulat; MA by Nikolaos Mastrantonas