Churning Atmospheric Winds Inspire Extreme Weather

In trying to explain for recent prolonged bouts of unseasonal and extreme weather patterns, researchers have found that changes in atmospheric wind patterns are causing certain regions to become more vulnerable to extreme conditions.

Parts of the Northern Hemisphere in particular, researchers from the University of Exeter and the University of Melbourne say, are facing the most extreme of weather conditions due to these changes.

A study details these findings in the journal Nature Climate Change.

"The impacts of large and slow moving atmospheric waves are different in different places. In some places amplified waves increase the chance of unusually hot conditions, and in others the risk of cold, wet or dry conditions," explained James Screen, lead author of the study.

According to the study, changes in the wave-like path that high-altitude winds take from west to east influence temperature and precipitation. Either warm air is sucked from the tropics, or cold air is taken from the Arctic and carried to the United States, Northern and Central Europe, or Asia - creating unseasonal bouts of cold or hot weather. Rainfall is also guided toward or away from these regions by sudden changes in airflow patterns.

Examining atmospheric patterns for causes of heat waves, cold spells, droughts and deluges, the researchers found that North America (NA) is facing the most increased types of climate change. Using data from extreme weather patterns between 1979 and 2012, they found that the continent faces an increasing chance of droughts in central NA, heat waves in western NA and prolonged extreme cold in eastern NA.

Western Asia is due for prolonged wet spells, while in contrast, central Asia faces more heat waves and droughts than is common for the region. Europe also faces an unusual vulnerability to drought.

The researchers hope to use this data to better predict how the atmosphere will continue to change, and how these changes will impact the world.

"The findings are very important for decision makers in assessing the risk of, and planning for the impacts of, extreme weather events in the future," co-author Ian Simmonds said in a statement.

The study was published in Nature Climate Change on June 22.