A decrease in storm activity over large parts of the US, Europe, Russia, and China is found to influence weather extremes – cold ones in winter, hot or dry ones in summer. This is now shown in a study by scientists from the Potsdam Institute for Climate Impact Research. The observed changes in storm activity are likely related to changes in other atmospheric dynamics like the jet stream – strong westerly winds circling the Northern hemisphere high up in the sky.
“Less or less severe storms in the mid-latitudes, this at first sight seems to be good news – but unfortunately it isn’t,” says lead-author Jascha Lehmann. “These storms have a moderating effect on land temperatures as they bring maritime air from the oceans to the continents and a lack of them can thus favor extreme temperatures.”
In the Northern Hemisphere mid-latitudes, much of the day-to-day weather variability is determined by the storm track regions located over the Atlantic and Pacific oceans. Here, weather systems, including storms, are generated and travel eastwards to the continents.
In winter, storms bring air from the relatively warm oceans to the continents and thus have a warming effect. In summer, the effect reverses with winds bringing relatively cool and moist air from the sea. The authors show that a lack of such weather systems can thus favor more persistent heat and drought events in summer, and cold spells in winter.
“This summer a severe drought in China’s northern bread basket region Liaoning threatened crop yields, while California has been experiencing a prolonged drought for no less than three consecutive years,” says Lehmann. Comprehensive analysis of satellite weather data shows that these are indeed regions where significant reductions in storm activity are detected during the rainy season.
In summer, storm activity calmed down over as much as 80 percent of the land area in the mid-latitudes. In winter the changes are more patchy, yet pronounced reductions are found over eastern US and large parts of Europe and Asia. This includes regions like New York and Chicago which suffered from record-breaking cold temperatures in recent winters.
These detected changes in mid-latitude storm tracks are likely linked to changes in the jet stream and planetary waves in the atmosphere. Such dynamical changes favor certain types of weather situations in some regions and others elsewhere.
“Regional changes are mostly due to natural variability but on top of that we see this pronounced overall weakening in summer storm activity,” says co-author Dim Coumou, ”This is also something projected by climate models under future emission scenarios. However, the data so far is not sufficient to say whether the storm activity changes are caused by climate change – this has to be investigated further.”
Although average summer storm activity decreases, the most intense winter storms are projected to increase in frequency under continued global warming. This could have severe implications for heavy rainfall events. Also, the most intense hurricanes and typhoons in the tropics are likely to increase under future warming because they’re driven by rising ocean surface temperatures.
In the Northern mid-latitudes, the main driver is the temperature difference between the warm equator and the cold Arctic; a difference that is shrinking because man-made warming is over-proportionate in the Arctic.
“Altogether our study highlights how sensitive regional weather conditions are to any changes in large-scale atmosphere dynamics,” says Coumou. “This can have serious impacts for people on the ground.”
Article: Lehmann, J., Coumou, D. (2015): The influence of mid-latitude storm tracks on hot, cold, dry and wet extremes. Nature Scientific Reports. [DOI 10.1038/srep17491]
For further information please contact:
PIK press office
Phone: +49 331 288 25 07
Mareike Schodder | Potsdam-Institut für Klimafolgenforschung
Ice cave in Transylvania yields window into region's past
28.04.2017 | National Science Foundation
Citizen science campaign to aid disaster response
28.04.2017 | International Institute for Applied Systems Analysis (IIASA)
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences