Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Trapped atmospheric waves triggered more weather extremes

12.08.2014

Weather extremes in the summer - such as the record heat wave in the United States that hit corn farmers and worsened wildfires in 2012 - have reached an exceptional number in the last ten years.

Man-made global warming can explain a gradual increase in periods of severe heat, but the observed change in the magnitude and duration of some events is not so easily explained. It has been linked to a recently discovered mechanism: the trapping of giant waves in the atmosphere. A new data analysis now shows that such wave-trapping events are indeed on the rise.

“The large number of recent high-impact extreme weather events has struck and puzzled us,” says Dim Coumou, lead author of the study conducted by a team of scientists from the Potsdam Institute for Climate Impact Research (PIK).

“Of course we are warming our atmosphere by emitting CO2 from fossil fuels, but the increase in devastating heat waves in regions like Europe or the US seems disproportionate.” One reason could be changes in circulation patterns in the atmosphere. By analysing large sets of global weather data, the researchers found an intriguing connection.

... more about:
»Arctic »CO2 »PIK »PNAS »atmosphere »circulation »fossil fuels »heat »mechanism »waves

Rossby Waves: meandering airstreams

An important part of the global air motion in the mid-latitudes normally takes the form of waves wandering around the globe, called Rossby Waves. When they swing north, they suck warm air from the tropics to Europe, Russia, or the US; and when they swing south, they do the same thing with cold air from the Arctic.

However, the study shows that in periods with extreme weather, some of these waves become virtually stalled and greatly amplified. While a few warm days have little impact, effects on people and ecosystems can be severe when these periods are prolonged.

“Behind this, there is a subtle resonance mechanism that traps waves in the mid-latitudes and amplifies them strongly,” says Stefan Rahmstorf, co-author of the study to be published in the Proceedings of the US National Academy of Sciences (PNAS). Using advanced data analysis, the new study shows that when certain resonance conditions are fulfilled, the atmosphere tends to develop anomalously slowly propagating waves with large amplitudes, typically associated with extreme weather on the ground.

An important finding is that this phenomenon is occurring more often: After the year 2000, it has been almost twice as frequent as before. “Evidence for actual changes in planetary wave activity was so far not clear. But by knowing what patterns to look for, we have now found strong evidence for an increase in these resonance events.”

The Arctic factor: warming twice as fast as most other regions

Why would these events be on the rise? Both theory and the new data suggest a link to processes in the Arctic. Since the year 2000, the Arctic is warming about twice as fast as the rest of the globe. One reason for this is that because the white sea ice is rapidly shrinking, less sunlight gets reflected back into space, while the open ocean is dark and hence warms more.

“This melting of ice and snow is actually due to our lifestyle of churning out unprecedented amounts of greenhouse gases from fossil fuels,” says Hans Joachim Schellnhuber, co-author of the study and director of PIK. As the Arctic warms more rapidly, the temperature difference to other regions decreases. Yet temperature differences are a major driver of the atmospheric circulation patterns that in turn rule our weather.

“The planetary waves topic illustrates how delicately interlinked components in the Earth system are.” Schellnhuber concludes: "And it shows how disproportionately the system might react to our perturbations.”

Article: Coumou, D., Petoukhov, V., Rahmstorf, S., Petri, S., Schellnhuber, H.J. (2014): Quasi-resonant circulation regimes and hemispheric synchronization of extreme weather in boreal summer. Proceedings of the US National Academy of Sciences PNAS [DOI:10.1073/pnas.1412797111]

Weblink where the article will be published: www.pnas.org/cgi/doi/10.1073/pnas.1412797111

For further information please contact:
PIK press office
Phone: +49 331 288 25 07
E-Mail: press@pik-potsdam.de
Twitter: @PIK_Climate

Jonas Viering | PIK Potsdam
Further information:
http://www.pik-potsdam.de

Further reports about: Arctic CO2 PIK PNAS atmosphere circulation fossil fuels heat mechanism waves

More articles from Earth Sciences:

nachricht California rising
04.09.2015 | University of California - Santa Barbara

nachricht NASA's Aqua Satellite sees Typhoon Kilo headed west
04.09.2015 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Hubble survey unlocks clues to star birth in neighboring galaxy

In a survey of NASA's Hubble Space Telescope images of 2,753 young, blue star clusters in the neighboring Andromeda galaxy (M31), astronomers have found that M31 and our own galaxy have a similar percentage of newborn stars based on mass.

By nailing down what percentage of stars have a particular mass within a cluster, or the Initial Mass Function (IMF), scientists can better interpret the light...

Im Focus: Fraunhofer ISE Develops Highly Compact Inverter for Uninterruptible Power Supplies

Silicon Carbide Components Enable Efficiency of 98.7 percent

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE have developed a highly compact and efficient inverter for use in uninterruptible power...

Im Focus: How wind sculpted Earth's largest dust deposit

China's Loess Plateau was formed by wind alternately depositing dust or removing dust over the last 2.6 million years, according to a new report from University of Arizona geoscientists. The study is the first to explain how the steep-fronted plateau formed.

China's Loess Plateau was formed by wind alternately depositing dust or removing dust over the last 2.6 million years, according to a new report from...

Im Focus: An engineered surface unsticks sticky water droplets

The leaves of the lotus flower, and other natural surfaces that repel water and dirt, have been the model for many types of engineered liquid-repelling surfaces. As slippery as these surfaces are, however, tiny water droplets still stick to them. Now, Penn State researchers have developed nano/micro-textured, highly slippery surfaces able to outperform these naturally inspired coatings, particularly when the water is a vapor or tiny droplets.

Enhancing the mobility of liquid droplets on rough surfaces could improve condensation heat transfer for power-plant heat exchangers, create more efficient...

Im Focus: Increasingly severe disturbances weaken world's temperate forests

Longer, more severe, and hotter droughts and a myriad of other threats, including diseases and more extensive and severe wildfires, are threatening to transform some of the world's temperate forests, a new study published in Science has found. Without informed management, some forests could convert to shrublands or grasslands within the coming decades.

"While we have been trying to manage for resilience of 20th century conditions, we realize now that we must prepare for transformations and attempt to ease...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Together - Work - Experience

03.09.2015 | Event News

Networking conference in Heidelberg for outstanding mathematicians and computer scientists

20.08.2015 | Event News

Scientists meet in Münster for the world’s largest Chitin und Chitosan Conference

20.08.2015 | Event News

 
Latest News

Ion implanted, co-annealed, screen-printed 21% efficient n-PERT solar cells with a bifaciality >97%

04.09.2015 | Power and Electrical Engineering

Casting of SiSiC: new perspectives for chemical and plant engineering

04.09.2015 | Machine Engineering

Extremely thin ceramic components made possible by extrusion

04.09.2015 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>