Higher pressure over the North American continent and Greenland are driving recent changes in the wind patterns across the Arctic, which are impacting sea ice and could bring changes to the weather across North America and Europe, according to a new study that was led by NOAA.
Researchers examined the wind patterns in the subarctic in the early summer between 2007 and 2012 as compared to the average for 1981 to 2010. They discovered that the previously normal west-to-east flowing upper-level winds have been replaced by a more north-south undulating, or wave-like pattern, according to the NOAA news report.
This new wind pattern transports warmer air into the Arctic and pushes Arctic air farther south toward the mid-latitudes, potentially leading to more persistent weather patterns.
Negative phase of the Arctic Oscillation (higher pressures over the Arctic), which forces cold air farther south into the mid-latitudes
Enhanced warming of the Arctic affects the jet stream by slowing its west-to-east winds and by promoting larger north-south meanders in the flow, according to NOAA.
However, predicting those meanders and where the weather associated with them will be located in any given year, however, remains a challenge, according to NOAA.
For example, the previous two winters were very different from one another in North America. There was strong high pressure blocking in the northern latitudes both winters, but the position of these high pressure ridges was very different. Knowing where these blocking highs set up during long periods of the winter is crucial to the forecasts.
The researchers say that with more solar energy going into the Arctic Ocean because of lost ice, there is reason to expect more extreme weather events, such as heavy snowfall, heat waves, and flooding in North America and Europe but these will vary in location, intensity, and timescales. (from NOAA)
As the Arctic warms at twice the global rate, we expect an increased probability of extreme weather events across the temperate latitudes of the northern hemisphere, where billions of people live," said Jennifer Francis, Ph.D, of Rutgers. (from NOAA)
The study, entitled "The Recent Shift in Early Summer Arctic Atmospheric Circulation," was co-authored by scientists from Rutgers University in New Jersey, the University of Sheffield in the United Kingdom, and the Joint Institute for the Study of the Atmosphere and Ocean, a partnership of NOAA and the University of Washington.
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