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
Ten-year anniversary of the Neumayer Station III
18.01.2019 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
The pace at which the world’s permafrost soils are warming
16.01.2019 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
The scientific and political community alike stress the importance of German Antarctic research
Joint Press Release from the BMBF and AWI
The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
18.01.2019 | Materials Sciences
18.01.2019 | Life Sciences
18.01.2019 | Health and Medicine