A 2020 news report (H/T Belfast Telegraph) headlined Extreme weather being caused by jet stream ‘not because of Arctic warming’, with the sub-heading: ‘Any link is more likely to be a result of random fluctuations in the jet stream influencing Arctic temperatures, researchers say’ – cites a study that comprehensively contradicts the findings described in the article below. “The well-publicised idea that Arctic warming is leading to a wavier jet stream just does not hold up to scrutiny”, said Professor James Screen [University of Exeter]. “With the benefit of 10 more years of data and model experiments, we find no evidence of long-term changes in waviness despite on-going Arctic warming.” But the stated lack of evidence hasn’t deterred this new research. Are they flogging the proverbial dead horse?
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A quartet of researchers, two with the Nordic Institute for Theoretical Physics and two with Pukyong National University, has created a group of simulations of changes to the jet stream under global warming, says Phys.org.
In their paper published in Proceedings of the National Academy of Sciences, the group describes using math theory to describe wind motion under given circumstances to create their simulations.
Over the past several years, the jet stream has become wavier than it used to be. Both peaks and valleys have become more extreme.
This has led to changes in weather patterns—some places have grown wetter and some drier, and there have also been more extended hot and cold spells around the globe.
In this new effort, the researchers suspected that the reason for the increased waviness is due to the asymmetric rise in global temperatures. Global warming is heating up the Arctic much faster than it is heating up more southern areas. The result is big changes in winds in the upper atmosphere.
To test their theory, the researchers used math formulas to represent wind flow under historical patterns. They then added the impact of warming air, taking into account the differences above and below the jet stream.
They used their formulas to simulate wind flow across the northern part of the planet that make up the jet stream. The simulations showed what the researchers were expecting—more waviness.
Full article here.
via Tallbloke’s Talkshop
September 18, 2022, by oldbrew