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idunno

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WACCY Science
« on: February 17, 2014, 04:16:40 AM »
WACCY stands for Warm Arctic Cold Continents - the predicition being that, as the Arctic warms, this will cause cooling of North America and Eurasia.

Given this winter's weather so far, this paper from Cohen et al is looking topical and smart...

http://www.tos.org/oceanography/archive/26-4_cohen.html

Abstract

Arctic sea ice was observed to be at a new record minimum in September 2012. Following this summer minimum, northern Eurasia and much of North America experienced severe winter weather during the winter of 2012/2013. A statistical model that used Eurasian snow cover as its main predictor successfully forecast the observed cold winter temperatures. We propose that the large melting of Arctic sea ice may be related to the rapid advance of snow cover, similar to the connection made in studies of past climates between low Arctic sea ice and enhanced continental snowfalls and glacial inception via ice sheet growth. Regressions between autumnal sea ice extent and Eurasian snow cover extent and Northern Hemisphere temperatures yield the characteristic "warm Arctic/cold continents" pattern. This pattern was observed during winter 2012/2013, and it is common among years with observed low autumn sea ice, rapid autumn snow cover advance, and a negative winter Arctic Oscillation. Dynamical models fail to capture this pattern, instead showing maximum warming over the Arctic Ocean and widespread winter warming over the adjacent continents. We suggest that the simulated widespread warming may be due to incorrect sea ice-atmosphere coupling, including an incorrect triggering of positive feedback between low sea ice and atmospheric convection, resulting in significant model errors that are evident in seasonal predictions and that potentially impact future climate change projections.

I have a hunch that earlier papers from Cohen may be a better place to start this topic. See/share below...

wili

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Re: WACCY Science
« Reply #1 on: February 17, 2014, 06:14:55 AM »
Thanks for starting this, i.

One of the oldest predictions I know of for the immediate effects of low levels of Arctic sea ice is that there would be increased fall and early winter snow in the upper latitudes, such as Siberia. That such increases in snow cover would have effects on the shape of the jet stream (and of the polar vortex, perhaps?) would not be at all surprising to me.

I just haven't seen these all put together in a published paper before. As i points out, we may have to dig deeper into the complete oeuvre of this scholar to get the full details, but it is worth looking into, imvvho.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

idunno

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Re: WACCY Science
« Reply #2 on: February 17, 2014, 12:31:40 PM »
There's also a whole post from Neven, which makes a much better introduction than my first post above, here...

http://neven1.typepad.com/blog/2012/03/wacc-overview.html

HT Jim Hunt.

ChrisReynolds

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Re: WACCY Science
« Reply #3 on: February 17, 2014, 01:53:23 PM »
Thanks for posting this, I'd missed this paper.

Cohen's been covering this issue for some years. To quote from a blog post of mine (I think it's one of the ones Dr Cohen has seen and approved of):



Quote
A) Arctic Temperature increase - There's bit of feedback here as sea-ice loss is a large part of Arctic amplification.

B) As a result of the warming sea-ice declines in volume leading to a decline in September sea-ice extent.

C) Increase in mean lower tropospheric moisture. As the atmosphere warms the Clausius Clapyron relationship allows for a higher level of water vapour to be held in the warmer air. Also increased amounts of open water in the Arctic provide more water vapour as there's more open ocean for evaporation to take place from.

D) The increased atmospheric humidity allows for an increase in October Eurasian snow cover*.

E) The increased October Eurasian snow cover causes a decrease in the December/January/February AO index. This then leads to the observed cooling pattern in late winter Northern Hemisphere.

*Kurita N (2011) Origin of Arctic water vapor during the ice-growth season. Geophys
Res Lett, 10.1029/2010GL046064 - that shows (using isotopic signatures) that increased moisture transport  from extensive open water in the autumn is detected in Siberia, but by winter (when the Arctic Ocean is frozen) the source of moisture is from mid lattitudes.


Quote
Recent extreme minima in Arctic summer sea ice extent have led to enhanced heat flux from the ocean to the atmosphere. This change may increase the humidity in Arctic air masses during the ice-growth season. Humidity increases may also be sustained by enhanced moisture transport into the Arctic and the relative influence of local- versus distant-moisture sources remains uncertain. Here we examined the predominant origin of Arctic water vapor during the ice-growth period, using water isotopologues (HDO, H218O) as tracers. An exploration of the isotopic evolution of surface water vapor in the Arctic Ocean found that isotopic values of moisture originating from the Arctic Ocean were characterized by higher d-excess values, a second-order isotopic parameter, than those of moisture originating from lower latitudes. These high d-excess values (>20‰) in Arctic-origin air masses were observed in mid-autumn. Subsequently, high d-excess values gradually decreased to the global average (d = 10) and disappeared in early winter, when sea ice covered a large part of the Arctic Ocean. This change suggests that the humidity source of Arctic air masses switches in early winter from locally driven to moisture transport from lower latitudes.
http://onlinelibrary.wiley.com/doi/10.1029/2010GL046064/abstract

idunno

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Re: WACCY Science
« Reply #4 on: November 22, 2016, 01:52:36 PM »
This seems like it's worth a bump.

Also, Dr Cohen has started to post what are promised to be regular updates on the Arctic Oscillation...

https://www.aer.com/science-research/climate-weather/arctic-oscillation

...much of which goes over my head. But on previous form, he's well worth paying attention to.

idunno

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Re: WACCY Science
« Reply #5 on: December 19, 2016, 05:53:32 PM »
Idunno, as ever, if this is the right thread, but the following long Guardian article examines the mounting evidence that Jennifer Francis's speculations about the weakening jetstream are looking increasingly vindicated, and examines some of the consequences...

https://www.theguardian.com/environment/2016/dec/19/arctic-ice-melt-already-affecting-weather-patterns-where-you-live-right-now

crandles

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Re: WACCY Science
« Reply #6 on: September 03, 2021, 01:03:27 PM »
https://www.science.org/doi/10.1126/science.abi9167

Quote
Linking Arctic variability and change with extreme winter weather in the United States

The Arctic is warming at a rate twice the global average and severe winter weather is reported to be increasing across many heavily populated mid-latitude regions, but there is no agreement on whether a physical link exists between the two phenomena. We use observational analysis to show that a lesser-known stratospheric polar vortex (SPV) disruption that involves wave reflection and stretching of the SPV is linked with extreme cold across parts of Asia and North America, including the recent February 2021 Texas cold wave, and has been increasing over the satellite era. We then use numerical modeling experiments forced with trends in autumn snow cover and Arctic sea ice to establish a physical link between Arctic change and SPV stretching and related surface impacts.

getting some coverage eg
https://www.bbc.co.uk/news/science-environment-58425526

Climate change: Arctic warming linked to colder winters