Scientists find 'traffic jams' in jet stream cause abnormal weather patterns
New Delhi : A new study gives an explanation for a strange and deadly weather pattern in which the jet stream, the air current that encircles the Earth, stalls out over a region. Researchers said that the pattern are much like highways, has a capacity to exceed and create blockages that are remarkably similar to traffic jams and climate forecasters can apply the same math to model them both.
The sky sometimes has its limits, according to new research from two University of Chicago atmospheric scientists.
The deadly weather phenomenon known as “blocking” can be explained by citing about the 2003 European heat wave, the2014 drought in California and the swing of Superstorm Sandy in 2012 that actually surprised weather forecasters. In those situations the jet stream meanders, weather system was stopped from moving eastward. Scientists have known about it for decades, almost as long as they've known about the jet stream which was first discovered by pioneering University of Chicago meteorologist Carl-Gustaf Rossby. However, no one had a good explanation for why such weather conditions happened.
“Blocking is notoriously difficult to forecast, in large part because there was no compelling theory about when it forms and why," said study coauthor Noboru Nakamura, a professor in the Department of the Geophysical Sciences.
Nakamura and then-graduate student Clare S.Y. Huang were studying about the jet stream, trying to find out sizes for blocking in order to have better analysis of the phenomenon. One of their new metrics was a term that measured the jet stream's meander. Looking over the math, Nakamura realized that the equation was nearly identical to one worked out decades ago by transportation engineers trying to describe the cause of traffic jams.
"It turns out the jet stream has a capacity for 'weather traffic,' just as highway has traffic capacity, and when it is exceeded, blocking manifests as congestion," said Huang.
Much like car traffic, movement slows when multiple highways converge and the speed of the jet stream is condensed due to geography such as mountains or coasts.
The result comes out to be a simple theory that not only reproduces blocking, but predicts it, said Nakamura, who called making the cross-disciplinary connection "one of the most unexpected, but enlightening moments in my research career -- truly a gift from God."
The description may not immediately improve short-term weather forecasting, the researchers said, but it will certainly help forecast long-term patterns, including which areas may face more drought or floods.
Their preliminary results suggest that while climate change probably increases blocking by running the jet stream closer to its capacity, there will be local differences "It's very difficult to forecast anything until you understand why it's happening, so this mechanistic model should be extremely helpful," Nakamura said.
And the model, unlike most modern climate science, is computationally simple: "This equation captures the essence with a much less complicated system," Huang said.