Jet stream not getting ‘wavier’ despite Arctic warming, say researchers

Posted: February 20, 2020 by oldbrew in data, modelling, Natural Variation, research, wind
Tags: , ,

Credit: Wikipedia


This contradicts climate alarmist claims such as: Global Warming Is Messing with the Jet Stream. Whether 40 years of data is enough to establish what is ‘normal’, is another matter. The fastest jetstream on record of 231 mph has only just been set, we’re told.
– – –
Rapid Arctic warming has not led to a “wavier” jet stream around the mid-latitudes in recent decades, pioneering new research has shown.

Scientists from the University of Exeter have studied the extent to which Arctic amplification—the faster rate of warming in the Arctic compared to places farther south—has affected the fluctuation of the jet stream’s winding course over the North Hemisphere, reports Phys.org.

Recent studies have suggested the warming Arctic region has led to a “wavier” jet stream—which can lead to extreme weather conditions striking the US and Europe.

However, the new study by Dr. Russell Blackport and Professor James Screen, shows that Arctic warming does not drive a more meandering jet stream.

Instead, they believe any link is more likely to be a result of random fluctuations in the jet stream influencing Arctic temperatures, rather than the other way around.

The study is published in leading journal Science Advances on Wednesday 19 February 2020.

Dr. Blackport, a Research Fellow in Mathematics and lead author of the study, said: “While there does appear to be a link between a wavier jet stream and Arctic warming in year-to-year and decade-to-decade variability, there has not been a long-term increase in waviness in response to the rapidly warming Arctic.”

Scientists have studied whether the jet stream’s meandering course across the Northern Hemisphere is amplified by climate change in recent years.

For about two decades, the jet stream—a powerful band of westerly winds across the mid-latitudes—was observed to have a “wavier” flow, which coincided with greater Arctic warming through climate change.

These waves have caused extreme weather conditions to strike mainland Europe and the US, bringing intense cold air that leads to extreme cold weather.

In this new study, Dr. Blackport and Professor Screen studied not only climate model simulations but also the observed conditions going back 40 years.

They found that the previously reported trend toward a wavier circulation during autumn and winter has reversed in recent years, despite continued Arctic amplification.

This reversal has resulted in no long-term trends in waviness, in agreement with climate model simulations, which also suggest little change in “waviness” in response to strong Arctic warming.

The results, the scientists say, strongly suggest that the observed and simulated link between jet stream “waviness” and Arctic temperatures do not represent a causal effect of Arctic amplification on the jet stream.

Professor Screen, an Associate Professor in Climate Science at Exeter added: “The well-publicised idea that Arctic warming is leading to a wavier jet stream just does not hold up to scrutiny.

“With the benefit of ten more years of data and model experiments, we find no evidence of long-term changes in waviness despite on-going Arctic warming.”

Full report here.

Comments
  1. Jaime Jessop says:

    “Despite substantial scientific uncertainty, the Francis and Vavrus hypothesis has become a regular narrative in media reporting of extreme weather events (33–35). This widespread media reporting is likely a major reason why there is high public belief that if Arctic warming continues, it will have major effects on midlatitude weather (33). Some scientists argue that the possible effects of Arctic amplification on the circulation have been overstated in the public discourse and distracted from other more certain and no less concerning consequences of climate change (36).”

    Climate alarmists’ extreme weather meme. Busted. Oh dear, with RCP8.5 now busted too, they’re running out of excuses for the rapid imposition of the eco-socialist brave new world regime. Still, there’s always tipping points when all else fails.

  2. dennisambler says:

    S Wales Echo 3rd December 1891
    “SEVERE WINTER PREDICTED. Professor Walter H. Smith, the best known meteorologist in Canada, has made a prediction full of painful interest for all of us. He says that Europe will experience another very severe winter. Professor Smith also says that the Atlantic voyages will prove to be the roughest on record.

    The bad weather in England and the extensive drought in America are due, according to this prophet, to the exceptionally southern course taken by the great Continental and oceanic wind areas.”

    Presumably this was the jet stream before it became famous.

  3. oldbrew says:

    The bad weather in England

    Just like now: 4-5 days of strong wind and heavy rain every week during this month – still going on.

    UK weather: Parts of UK could see a month’s rain in 24 hours amid floods
    33 minutes ago
    https://www.bbc.co.uk/news/uk-51567635

  4. Jaime Jessop says:

    Oldbrew,

    Yes, that would be the fast moving, powerful, zonal jet stream generated by a tight polar vortex – which is due to climate change!

    https://cliscep.com/2019/11/25/climate-change-to-world-honey-i-shrunk-the-jet-stream/

  5. JB says:

    Nature’s of the “brass ring” that befuddles analysts, just as my TV course professor described in college.

    Its the age of Fixation, driven by ideology. A primary attribute of Chicken Little.

  6. BLACK PEARL says:

    Once read on Piers Corbyn’s web site that it was a weakening solar cycle that led to meandering jet steams …

  7. rogercaiazza says:

    Very disappointing that they did not use the https://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis.html data that goes back another 30 years.

  8. Tish Farrell says:

    I’ve been reading the Arctic is pretty cold this year with good ice forming: https://www.natice.noaa.gov/pub/ims/ims_v3/ims_gif/ARCHIVE/EuAsia/2020/ims2020050_asiaeurope.gif
    Also Alaska below usual temps. Meanwhile in the UK we’ve been having wild wet weather.

  9. Stephen Richards says:

    That might be a problem now because the arctic ice is back to normal. Now, when I was reading, HH Lamb many years ago (about 50), he hypothesised that a cooling planet would create a wavy jetstream. This was because a warming planet would reduce the temperature gradient from north to south (NH) and south to north (SH) hence reduce extreme weather outbreaks. However, he also wrote that a cooling planet would bring more anticyclonic blocking and therefore more drought, more rain, more cold and more heat. That is to say that blocking would create long periods of one weather type and wavy jetsreams would be the norm.

    Et VOILà, Qu’est ce qu’on voir ?

  10. Stephen Riochards says:

    Jaime Jessop says:
    February 20, 2020 at 11:49 am

    Hello Jaime. It’s good to hear from you again. I’m coming to live in england hopefully this year. Will probably buy a house somewhere between yorkshire and north norfolk.

  11. Stephen Riochards says:

    oldbrew says:
    February 20, 2020 at 11:30 am

    I was in the east of england in the 90s at a conference . We had a strom every thurday for a month. Kelvin wave ? The same as this month ? There seems to be a change in pattern coming in about 10 to 14 days but it’s a long way off.

  12. Is Stephen Wilde still doing research on the jet stream? Haven’t heard anything for a while now…

  13. Stephen Riochards says:

    Jaime Jessop says:
    February 20, 2020 at 11:49 am

    The system lost my second note to you. It’s good to see you are still around. I shall be coming to live in england and am looking for somewhere around linconshire and nth norfolk

  14. pochas94 says:

    Reminds me of the transition region where laminar flow becomes turbulent. As you increase the flow velocity in a pipe or other conduit the pressure drop will at first increase (laminar flow) but suddenly the flow will become turbulent and the pressure drop will decrease (transition region), until with further increase in flow the pressure drop will again increase (turbulent flow). Engineers use the Reynolds number to predict these changes. Could the jet streams show similar behavior?

  15. oldbrew says:

    BBC interviewed a professor today who was talking about atmospheric rivers, referring to what Britain is currently experiencing.

    https://www.noaa.gov/stories/what-are-atmospheric-rivers

  16. pochas94 says:

    Further to above, the curve of flow vs pressure drop has more than one flow which gives the same pressure drop, suggesting that fluids in motion can spontaneously jump from one state to another.

  17. phil salmon says:

    This is what Judah Cohen has to say on his AER atmospheric blog page, as of 17 Feb:

    I know I am dating myself but what comes to mind as I sit down to write another blog is “Tune in tomorrow—same Bat-time, same Bat-channel!” I could just as easily write tune in next week same positive AO same strong PV. The AO remains positive and the PV remains strong both even flirting with records with no real change in the foreseeable future (Figures 1 & 11). I did check historical winter polar cap geopotential height anomalies (PCHs), and the stretch of universally cold tropospheric and stratospheric PCHs that we observed this winter is extremely rare. The closest that I could find is the winter of 1975/76. When cold PCHs dominated the stratosphere and troposphere right through the end of March. In general, I don’t like using data before 1979 but I could not find anything analogous since 1979 with 1989/90 being the closest. Though in February 1990 there was a sudden stratospheric warming (see Figure i). So there is precedent, though rare, for the positive AO/strong PV to continue right through March.

  18. Phoenix44 says:

    “…studied not only models but observations…”

  19. Jim says:

    Hydraulics shows us laminar flows, in pipes, and open spaces. And the difference in gradient. But does not show inputs to a system. Or where the input starts. The pump is always hidden, but, no pump, no flow. Now add in chaos, elevation, a nozzle, a pump. Water will flow,as a stream, but, look, there are inputs. Those inputs create turbulence, since the input is not evenly distributed, but varies. The stream output will vary. The same applies to moving air, or air moving, they probably have never seen the ball in a smokey atmosphere, then rotate the ball, how patterns change, just by rotating the ball, or, moving the ball. Or did the instructors forget a step, necessary to make the next step.

  20. Tim Spence says:

    They would be well advised to study the realtive stability of the Antarctic and ask themselves ‘why the difference?’. Russell and James are obviously not climate alarmists but in this case we have a Pole B, the South Pole, to compare and contrast.

  21. Damian Scott says:

    “They would be well advised to study the realtive stability of the Antarctic and ask themselves ‘why the difference?’. Russell and James are obviously not climate alarmists but in this case we have a Pole B, the South Pole, to compare and contrast”

    They aren’t really comparable. The North Pole has a few metres of sea ice whilst the South Pole has a few miles of pack ice on top of a continent.

  22. oldbrew says:

    Roy Clark dismantles some of the main warmist climate myths, with actual science.

    Clark, R., 2019, ‘The Greenhouse Effect’, Ventura Photonics Monograph, VPM 003.2, Thousand
    Oaks, CA
    August 2019

    http://venturaphotonics.com/files/The_Greenhouse_Effect.pdf

  23. Gamecock says:

    Mt. Washington, NH, experienced wind speed of 231 mph in April, 1934.

    A ground speed reading.

  24. Tim Spence says:

    Damian Scott “They aren’t really comparable.”

    That’s right but the differences are a good indicator of what might be going on!

    This study is quite something though, it starts off with the premise of Arctic amplification and warming affecting the jet stream and concludes that it isn’t happening. They don’t even say we need more money to study it more. That is not normal !!

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