New theory finds ‘traffic jams’ in jet stream cause abnormal weather patterns

Posted: May 24, 2018 by oldbrew in atmosphere, research, weather, wind
Tags: ,

Wavy jet stream
[image credit: BBC]

This could be a step forward in unravelling the whys and wherefores of the phenomenon of jet stream blocking.

The sky sometimes has its limits, according to new research from two University of Chicago atmospheric scientists.

A study published May 24 in Science offers an explanation for a mysterious and sometimes deadly weather pattern in which the jet stream, the global air currents that circle the Earth, stalls out over a region, reports

Much like highways, the jet stream has a capacity, researchers said, and when it’s exceeded, blockages form that are remarkably similar to traffic jams—and climate forecasters can use the same math to model them both.

The deadly 2003 European heat wave, California’s 2014 drought and the swing of Superstorm Sandy in 2012 that surprised forecasters—all of these were caused by a weather phenomenon known as “blocking,” in which the jet stream meanders, stopping weather systems from moving eastward.

Scientists have known about it for decades, almost as long as they’ve known about the jet stream—first discovered by pioneering University of Chicago meteorologist Carl-Gustaf Rossby, in fact—but no one had a good explanation for why it happens.

“Blocking is notoriously difficult to forecast, in large part because there was no compelling theory about when it forms and why,” said study co-author Noboru Nakamura, a professor in the Department of the Geophysical Sciences.

Nakamura and then-graduate student Clare S.Y. Huang were studying the jet stream, trying to determine a clear set of measurements for blocking in order to better analyze 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 devised decades ago by transportation engineers trying to describe 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 reduced due to topography such as mountains or coasts.

The result is 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.”

Continued here.

  1. craigm350 says:

    Reblogged this on WeatherAction News and commented:
    Piers Corbyn predicts the behavior of the Jetstream by lunar and solar activity. It’s hard to tell from this article and without seeing the full paper if this “finding” is really predictive or rather is descriptive by use of the traffic analogy. It doesn’t seem to say anything about why blocking and long stretches of the Jetstream seem to occur during periods of low solar activity. They do however make a statement about climate change that is as asinine as anything the Met Office have come up with in recent years to explain the Jetstream being naughty and not doing what they models said it should;

    Their initial results suggest that while climate change probably increases blocking by running the jet stream closer to its capacity, there will be regional differences: for example, the Pacific Ocean may actually see a decrease in blocking over the decades.

    And from the abstract;

    Climate change likely affects blocking frequency by modifying the jet stream’s proximity to capacity.

    Oh yikes, oh nos, it’s *probably* at capacity! Send us your cash in unmarked bills to behind the hot water pipes, third washroom along Victoria station. Pay up or the Jetstream gets capacity.

  2. oldbrew says:

    Report: the speed of the jet stream is reduced due to topography such as mountains or coasts.

    But: On Earth, the main jet streams are located near the altitude of the tropopause – Wikipedia

    Very few mountain ranges (except Himalayas, possibly Rockies and Andes) and no coasts anywhere near the tropopause :/

  3. p.g.sharrow says:

    From time to time we are asked what causes the creation of the Great Ice Mountains.
    Look at the picture above, the Canadian Shield and the wave loop out of the arctic. Polar cold meets Gulf moisture over Lake Superior. Similar wave over Western Europe meets Mediterranean moisture over Central Europe. Warm Ocean currents, weak solar heating of the atmosphere, results in loopy jets and Arctic cold spilling into mid-continental area of some elevation and snow, Heavy Snows. Now how long will this condition exist before winter snows result in persistent snow fields?…pg

  4. Paul Vaughan says:

    Recall that pink is the enlightened shade of red:

    The concrete details of a given construction may be messy, but if the construction satisfies a universal property, one can forget all those details: all there is to know about the construct is already contained in the universal property. Proofs often become short and elegant if the universal property is used rather than the concrete details.
    Universal properties occur everywhere in mathematics. By understanding their abstract properties, one obtains information about all these constructions and can avoid repeating the same analysis for each individual instance.

  5. tom0mason says:

    ““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.”

    IMO The driverless electric weather vehicles are being overcharged causing their satnav systems to become unstable. 🙂