Extreme weather events linked to stalling of planetary waves

06/11/2016 - Many extreme weather events in the Northern hemisphere have recently been accompanied by a stalling of huge airstreams high up in the atmosphere that normally circle our planet, taking the form of gigantic waves swinging up and down between the Tropics and the Arctic. Looking into the events of the summers three and four years ago, a new study by a team of scientists from the Potsdam Institute for Climate Impact Research finds that in fact a majority of extremes go with observed disturbances of the so-called planetary waves, adding evidence to the assumption that this connection might be of key importance.
Extreme weather events linked to stalling of planetary waves
Quasi resonant amplification in May 2015. Fig. 3 from Petoukhov et al, 2016

"While the physical mechanism has not yet been fully identified, the data from weather stations and satellites suggests that quasi-stationarity of planetary waves plays a potentially important role in the development of weather extremes under human-made global warming," says PIK-director Hans Joachim Schellnhuber, co-author of the study published in the Proceedings of the US National Academy of Sciences. "The increase of weather extremes is clearly greater than what would have to be expected from pure warming statistics, and we’re searching for the reasons of this observation."

When the planetary waves temporarily stop travelling and get greatly amplified by a phenomenon called resonance, they trap weather systems. Consequently, what otherwise might have been for instance just a few warm days can become a prolonged heat-wave, driving up the risks for health, crop yields, and forest fires. When a rain system gets trapped, the sustained local precipitation can saturate soils and result in dangerous floodings. Previous PIK research could show the link between planetary wave resonance and the 2010 Indus river flood in Pakistan and the 2011 heat wave in the USA.


Article: Petoukhov, V., Petri, S., Rahmstorf, S., Coumou, D., Kornhuber, K., Schellnhuber, H.J. (2016): Role of quasiresonant planetary wave dynamics in recent boreal spring-to-autumn extreme events. Proceedings of the National Academy of Sciences (PNAS). [doi:10.1073/pnas.1606300113]

Weblink to the article: http://www.pnas.org/content/early/2016/06/01/1606300113.abstract?sid=63419cfb-f54a-46d7-bf18-3cfb4ab0e6e2

Related reseach:
- https://www.pik-potsdam.de/news/press-releases/archive/2013/weather-extremes-provoked-by-trapping-of-giant-waves-in-the-atmosphere?searchterm=planetary+waves
- https://www.pik-potsdam.de/news/press-releases/archive/2014/trapped-atmospheric-waves-triggered-more-weather-extremes?searchterm=planetary+waves