Studying Planetary Waves to Predict Alpine Precipitation

Olivia Romppainen-Martius is the new assistant professor for climate change impact research at the Oeschger Centre. One of her research areas is to investigate the effects of climate change on heavy precipitation events in the Alps. Swiss Mobiliar insurance company finances her chair.

Over the years, Olivia Romppainen-Martius shifted her scientific focus from the snow pack and the Earth's surface to higher altitudes. The doctoral thesis of the specialist for climate dynamics dealt with "Aspects of wave disturbances on the tropopause and links to extreme weather in Europe." A better understanding of these so-called Rossby waves and links to various weather phenomena has been a main topic in her career; already when she was as visiting researcher at Columbia University and more recently when she held a postdoctoral position and worked as senior scientist at the ETH Zurich. Rossby waves are large-scale meanders of jet streams, which are responsible for weather patterns at mid-latitudes.

Improved climate models thanks to Rossby waves

The phenomenon itself has been known for quite some time. The subject of Olivia Romppainen-Martius' studies is to find out whether Rossby waves correlate with heavy precipitation in the Alps. She analyzed heavy precipitation events in the past 30 years and made the following interesting observation: "Many heavy precipitation events are preceded by a wave that we can trace back over six, seven days to its formation over the Pacific Ocean. This phenomenon is most relevant in the fall and winter months." Of particular interest is the finding that "there is a potential to reliably forecast such events because the atmosphere evolves less chaotically under the influence of a Rossby wave," she says.

Up until now, Olivia Romppainen-Martius' research evolved around the connection between Rossby waves forming over the Pacific and propagating towards Europa and heavy rain or snow fall events a week later in the Alps. Now, she also wants to apply her findings for a more accurate interpretation of climate scenarios. Today's models allow for accurate forecasts of global mean changes, particularly for temperature. It is, however, much more challenging to predict future changes for regional or local phenomena like precipitation. This is where Olivia Romppainen-Martius wants to make headway with her work, "We want to try and use Rossby waves' large-scale structures to enhance the conclusiveness of the models in the area of precipitation."

Climate impact on property insurance

The recently elected assistant professor places special emphasis on research that may one day allow meteorologists to predict heavy precipitation in the Alps. This is where Olivia Romppainen-Martius' scientific plans and the interest of the Mobiliar insurance company converge, and the reason why Mobiliar finances the extraordinary professorship for climate risk at the Oeschger Centre. The Mobiliar insurance company very deliberately places the research focus on the Alpine region. As one of Switzerland's leading property insurers it is directly affected by the consequences of climate change, in particular the increased occurrence of high impact weather events. The summer flood of 2005, for instance, led to 450 million Swiss francs worth of damage. "We want to understand climate trends so we can offer our clients the best coverage," said Mobiliar CEO Urs Berger when the company announced its engagement. The insurer will inject 5 million francs into climate research over the coming years in the hope of finding clues that may help prevent natural disasters – or at least reduce the damaging events.

Olivia Romppainen-Martius is excited to start an intense dialogue with the Mobiliar insurance company, discussing the company's needs and open questions regarding climate change risks in Switzerland. "I'm looking forward to conducting research that can be applied in practise. To achieve that we not only need profound knowledge of climate processes but also a constructive exchange of ideas with those who use our findings, so that our research meets their practical requirements." Olivia Romppainen-Martius learned from an earlier project focussing on the prediction of the pathways of tropical storms that the needs and requirements may vary widely according to the users: Swiss reinsurer Swiss Re for example was particularly interested in the intensity of hurricanes, while the local authorities, for example the mayor of New Orleans, would be more concerned whether the hurricane strikes the city or not. "Whether our data is relevant and useful for practical purposes very much depends on the application."

(2010)