Researchers at the University of Graz are investigating how warm Mediterranean temperatures influence the intensity of heavy rainfall in Austria. Their research helps to better understand the dynamics of extreme Mediterranean weather conditions.
Suddenly the temperatures drop by 20 degrees and it rains for days. Meteorologists call such extreme weather conditions, which are currently occurring in mid-September, Vb weather conditions (five-b). They are not uncommon in Austria, Slovenia, Hungary and Slovakia and always pose a real challenge for rescue workers. At the University of Graz, scientists from Douglas Maraun’s team are researching how climate change influences these weather conditions and their effects.
“These low-pressure areas form over the Mediterranean and move anti-clockwise south of the Alps to Austria,” explains the climate researcher. “The air accumulates on the mountains of the Eastern Alps and it starts to rain.” The temperature of the Mediterranean reached 27 degrees in August, which has a major influence on the intensity of the precipitation. “The air above it warms up and can then absorb a lot of moisture. This causes very heavy rain.”
As early as 2016, Maraun’s research group at the Wegener Center for Climate and Global Change investigated how high temperatures in the Mediterranean affect precipitation amounts in Austria. Using complex computer simulations, the researchers compared how the warming of the Mediterranean since the 1980s has changed precipitation along the path of Vb cyclones.
“The number of Vb cyclones remained roughly the same in the simulations, but at higher temperatures, evaporation over the Mediterranean increased significantly,” says the climate expert. “This means that more moisture was transported along the storm tracks, which led to more intense extreme precipitation in the simulations.” This situation is now also evident in reality.
“The cause of the currently high sea temperatures is not yet 100 percent clear,” says Maraun. “The long-term trend is largely due to climate change, but there are other factors.” For example, new emissions regulations for ships have been introduced to protect the environment. “It’s actually a paradox: we now have much cleaner air over the seas. But this also means that less sunlight is reflected, which further increases warming.” Due to climate change, we must expect an intensification of heavy rainfall in the future, the climate researcher concludes.
Contact: Douglas Maraun, Assoz. Prof. Dr. douglas.maraun@uni-graz.at +43 (0)316 380 – 8448 +43 (0)664 88326827 Mag. Roman Vilgut, MA Editor | Communications Officer Communications and Public Relations | Communications and Public Relations University of Graz | University of Graz Universitätsplatz 3/1, 8010 Graz T.: +43/(0)316/380 – 1017 M: +43/(0)660/3437615 E-Mail: roman.vilgut@uni-graz.at Web:
