Steig on Antarctic warming: “Rossby wave trains”

From the University of Washington, comes this upcoming paper by corresponding author Dr. Eric Steig (and co-authors)that the mechanism for warming of the Antarctic Peninsula is mostly weather pattern driven. The mechanism cited? “Rossby Wave Train” aka the circumpolar vortex aka the southern polar jet steam transferring warmth from the tropical Pacific.

I’ll have more on this after the UW press release below – Anthony

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West Antarctic warming triggered by warmer sea surface in tropical Pacific

By Vince Stricherz

News and Information

The Antarctic Peninsula has warmed rapidly for the last half-century or more, and recent studies have shown that an adjacent area, continental West Antarctica, has steadily warmed for at least 30 years, but scientists haven’t been sure why.

This station gathers weather information from a location near the middle of the West Antarctic Ice Sheet.

This station gathers weather information from a location near the middle of the West Antarctic Ice Sheet. Image: Heidi Roop

New University of Washington research shows that rising sea surface temperatures in the area of the Pacific Ocean along the equator and near the International Date Line drive atmospheric circulation that has caused some of the largest shifts in Antarctic climate in recent decades.

The warmer water generates rising air that creates a large wave structure in the atmosphere called a Rossby wave train, which brings warmer temperatures to West Antarctica during winter and spring.

Antarctica is somewhat isolated by the vast Southern Ocean, but the new results “show that it is still affected by climate changes elsewhere on the planet,” said Eric Steig, a UW professor of Earth and space sciences and director of the UW Quaternary Research Center.

Steig is the corresponding author of a paper documenting the findings that is being published April 10 in the journal Nature Geoscience. The lead author is Qinghua Ding, a postdoctoral researcher in the UW Quaternary Research Center. Co-authors are David Battisti, a UW atmospheric sciences professor, and Marcel Küttel, a former UW postdoctoral researcher now working in Switzerland.

The scientists used surface and satellite temperature observations to show a strong statistical connection between warmer temperatures in Antarctica, largely brought by westerly winds associated with high pressure over the Amundsen Sea adjacent to West Antarctica, and sea surface temperatures in the central tropical Pacific Ocean.

They found a strong relationship between central Pacific sea-surface readings and Antarctic temperatures during winter months, June through August. Though not as pronounced, the effect also appeared in the spring months of September through November.

The observed circulation changes are in the form of a series of high- and low-pressure cells that follow an arcing path from the tropical Pacific to West Antarctica. That is characteristic of a textbook Rossby wave train pattern, Ding said, and the same pattern is consistently produced in climate models, at least during winter.

Using observed changes in tropical sea surface temperatures, the researchers found they could account for half to all of the observed winter temperature changes in West Antarctica, depending on which observations are used for comparison.

“This is distinct from El Niño,” Steig said. That climate phenomenon, which affects weather patterns worldwide, primarily influences sea-surface temperatures farther east in the Pacific, nearer to South America. It can be, but isn’t always, associated with strong warming in the central Pacific.

Steig noted that the influence of Rossby waves on West Antarctic climate is not a new idea, but this is the first time such waves have been shown to be associated with long-term changes in Antarctic temperature.

The findings also could have implications for understanding the causes behind the thinning of the West Antarctic Ice Sheet, which contains about 10 percent of all the ice in Antarctica.

Steig noted that the westerly winds created by the high pressure over the Amundsen Sea pushes cold water away from the edge of the ice sheet and out into the open ocean. It is then replaced by warmer water from deeper in the ocean, which is melting the seaward edge of the ice sheet from below.

The work was funded by the National Science Foundation.

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In the northern hemisphere, Rossby waves look like this:

https://i1.wp.com/www.ees.rochester.edu/fehnlab/ees215/fig17_9.jpg

Source: http://www2.pvc.maricopa.edu/ssd/geog/outlines/GPH212/chap12.html

I’d show a Southern Hemisphere example of artwork like above, but there don’t seem to be any good ones handy. It isn’t studied that much in the SH because, well, so few people are affected by the weather the polar jet brings in the SH.

File:Jetstreamconfig.jpg

Here’s what they look like from satellite imagery over the south pole:

Satellite view of the atmospheric circulation at the South Pole. Source: NASA

Note that while the Antarctic peninsula is traversed by Rossby wave systems, the Antarctic main continent gets little such weather due to the strong, cold, Antarctic polar high.

 

I argued in April 2009:

What happens to Steig et al’s warming when you divide Antarctica into two distinct climate zones?

Köppen world climate classification

Köppen world climate classification - click to enlarge

As seen in the map above, currently Antarctica is classified per the Köppen climate classification system entirely as EF, or “Ice Cap”. But here is what it might look like if the peninsula was classified differently.

antarctic_climate_zones1

Jeff Condon did an analysis at my behest, removing the Antarctic Peninsula from the trend analysis of surface data and came up with this:

Now removing the peninsula does have basis in science because the ultra thin strip of land is primarily dependent on ocean temperatures and currents. It will be seen as cherry picking because I’ve clipped the part of the Antarctic warming the most. Before TCO or someone points out that I wouldn’t clip it if it didn’t have warming, keep in mind that I show it both with and without the peninsula and I make no claim that clipping the peninsula is the preferred method. It does make some sense though.

First the full trend.

nop-id-recon-total-trend 

Spatial trends with clipping region shown in black Figure 2.

Figure 2Figure 2 

As I’ve shown before, the trends from 1967 onward.

Figure 3Figure 3 

Spatial distribution 1967 onward.

Figure 4Figure 4 

If I’ve learned anything from all these plots, it’s that the Antarctic isn’t warming at 0.12 +/- 0.7 C/decade. It just isn’t. The actual trend is much lower than that and since 1967 it has even dropped a little across the continent.

Yep. It just isn’t.

There’s no signifcant trend in the Antarctic mainland when the peninsula is removed.

Of course, Jeff Condon and Ryan O’Donnell went on to show in a peer reviewed paper that the Mannian method of statistical treatment tended to smear all the warming from the Antarctic peninsula onto the mainland. See below:

Temperature trend Deg C/Decade Click to enlarge.

Now with Dr. Steig and co-authors showing that the Antarctic peninsula warming is affected mostly by weather related Rossby waves, it pretty much puts to rest the question of weather, not climate change for the Antarctic mainland.

I renew my call for a change in the Köppen climate classification system to make the Antarctic peninsula  to EM, “maritime polar” instead of EF,  “ice cap”. Clearly, the Antarctic peninsula is a different climate regime altogether and this new UW paper clearly illustrates how the peninsula’s climate is affected by synoptic scale systems that never affect the mainland.

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32 thoughts on “Steig on Antarctic warming: “Rossby wave trains”

  1. They could have left it the Palmer Peninsula, but noooo. I think they got what they had coming.
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  2. I wonder if he references his own 2009 paper for details of Antarctic warming or if references Jeff and Ryan’s 2011 paper.

  3. So…

    1) Antarctic cooling
    2) Not, really, the antarctic is warming if you spread the data just so…
    3) Man is the cause
    4) No, not really, the warming is driven by natural oscillations.
    5) Someone else says it’s not warming, the data spread was misleading.

    My compliments to all of those who make weather phenomenon their profession. I don’t have the patience of these kinds of exchanges. I think if forced to be a meteorologist I would insist on being stuck in a lab designing new sensors.

  4. As I have been pointing out for a couple of years now the Antarctic peninsula is a volcanic region which seems to be fairly active at the moment, it’s hard to tell since there is an awful lot of ice atop those volcanoes and we have few records. So all we can say is that there is quite a bit of geothermal heat there, but we cannot really either quantify it or indeed know how long this active phase has lasted.

    Personally I suspect it has a perceptible effect on the apparent warming there but there is no way to know for sure.

    Kindest Regards

  5. Minor tweak.
    ———————————————————-
    April 11, 2011 at 10:43 am

    So…

    1) Antarctic cooling
    2) Not, really, the antarctic is warming if you spread the data just so…
    3) Man Mann is the cause
    4) No, not really, the warming is driven by natural oscillations.
    5) Someone else says it’s not warming, the data spread was misleading.

    My compliments to all of those who make weather phenomenon their profession. I don’t have the patience of these kinds of exchanges. I think if forced to be a meteorologist I would insist on being stuck in a lab designing new sensors.

  6. Awesome! These researchers have re-discovered the Southern Hemisphere reflection of the Pacific Decadal Oscillation, which actually explains more variance in the SH than the NH during the past 30-60 years. Marvelous.

  7. Ryan Maue:

    Awesome! These researchers have re-discovered the Southern Hemisphere reflection of the Pacific Decadal Oscillation, which actually explains more variance in the SH than the NH during the past 30-60 years. Marvelous.

    And it was all their own work! No extra remedial help required!

  8. Steig noted that the westerly winds created by the high pressure over the Amundsen Sea pushes cold water away from the edge of the ice sheet and out into the open ocean. It is then replaced by warmer water from deeper in the ocean, which is melting the seaward edge of the ice sheet from below.

    So upwelling is the proximal cause with wind being the driver. It would be nice to see water temperature data for this hypothesis. Deep water ought to be near freezing.

  9. So it’s the weather afterall. Shock and horror! Hopefully they’ll now get of the continent and stop trying to ram the lie of AGW warming down our throats.

  10. Is the Antarctic Peninsula data another Hockey Stick grafted onto the Antarctic Ice Cap data?

  11. I haven’t had a chance to read this in any depth, but let’s not criticize Steig for simply publishing a new result. Is this approach correct or not? — that’s all that matters as far as I am concerned. Play the ball not the man.

  12. This echoes the paper that offered that boiling oceans off the US east coast were responsible for ice ages through Rossby waves…
    It looks like teh Rossby waves are the new recycled flavour of the day, signaling the complete bankrupcy of the IPCC climatologist when it comes to linking it to weather…
    One who must laugh out very loud is Marcel Leroux!

  13. The UW Press Release states:
    “The findings also could have implications for understanding the causes behind the thinning of the West Antarctic Ice Sheet, which contains about 10 percent of all the ice in Antarctica. ”

    In fact, a recent study concluded that the melting process there and elsewhere in Antartica has been going on for far too long to be blamed on increases in greenhouse gases. This was an impressive real world scientific study based on experimental measurements made by sending autonomous robot submarines to explore under the ice at the key Pine Island glacier (PIG) in the Amundsen Sea area, rather than model simulations. It states:

    “These site-specific processes notwithstanding, ice loss that extends beyond PIG
    and encompasses two neighbouring glacier basins implies a common cause, possibly related to the disappearance of a more extensive ice shelf in Pine Island Bay less than a century ago, triggering synchronous accelerations in its three tributary glaciers. Analogous signatures of ice sheet thinning have been observed at many locations around Antarctica where outlet glaciers terminate in the ocean. If these continentwide changes are driven by the same external forcing, they must all have a multidecadal, perhaps centennial, timescale, and basin-to-basin differences in the rates and spatial extent of the thinning must be associated with thresholds between fast and slow response in individual outlet glaciers.”

    The paper I refer to is “Observations beneath Pine Island Glacier in West Antarctica and implications for its retreat” Jenkins et al , published in Nature Geoscience 2010, freely available in pre-print format at http://eprints.soton.ac.uk/159453/1/Jenkins_preprint.pdf

  14. I’ve searched this post for the words CO2, Carbon Dioxide, Anthropogenic, Global Warming, Climate Change, Global Climate Disruption, Ozone Hole, and only managed to find the words “Climate Changes” but relating to a known oscillation in another part of the planet as the cause of the peninsula warming.

    I must assume that my microsoft search function is as broken as the GCM’s appear to be when it comes to understanding what is really happening with earth’s climate in order to remain on message with respect to the anthropogenic climate change hypothesis and predicted disaster for humanity.

    Maybe it’s a similar Rossby Wave Train that caused that tree in Yamal to get so warm.

  15. The peninsula antarctica is NOT a peninsula. It is an ISLAND.!! It is different as the antarctic continent. You need to view the new maps!!

  16. The more I’ve looked at it, I think the International Dateline area at the equator in the Pacific is really like the Earth’s thermostat.

    The largest changes in outgoing longwave radiation occur here (by orders of magnitude which can be as high as +/- 50 watts/m2). The atmospheric air circulation drives off of here to the rest of the planet as well. It tracks the global temperature pretty closely.

    But the driver of the OLR at the International Dateline area is the ENSO.

    OLR at the International Dateline versus the satellite temps (Global and Tropics).

    But more closely, they track the ENSO (Steig probably did not include this closer relationship in his paper since it is too obvious and takes away from the global warming storyline).

  17. “The work was funded by the National Science Foundation.”

    =====================================

    Sad, but true….the above piece of information is probably the most telling of anything that was said.

    Other than that, certainly nothing new under the sun.

    To quote Eisenhower:

    “The prospect of domination of the nation’s scholars by Federal employment, project allocations, and the power of money is ever present, and is gravely to be regarded.”

    Chris
    Norfolk, VA, USA

  18. From the UK Times 12th April 2011

    “Climate change may have been a factor in halving numbers of Adelie and chinstrap penguins in western Antarctica, a study suggests. The fall was related to a drop of up to 80 per cent in their main food, krill, due to rising temperatures and competition, scientists said in Proceedings of the National Academy of Sciences. ”

    Climate change, the phrase, is all that’s needed. Root cause doesn’t matter.

  19. So, the central portion of the Antarctic continent is isolated from the global climate to some extent by the circumpolar vortex. Which has in turn been intensified by the ozone loss from CFCs.

    Meanwhile the Antarctic penninsula is warming because the usual pattern of Rossby waves is carrying the rising sea surface temperature from warmer latitudes to the polar region.

    The Rossby waves are not the source of the warming, just the transport mechanism that carries that extra energy from the equitorial oceans which are warming to the pole.

  20. I have never really understood how all that increasing Antarctic undersea volcanic activity succeeds in not releasing heat.

  21. Bear in mind that 4 of the “Antarctic” BAS Reader stations used by Steig et al are far out in the ocean (Campbell 52.0S, Macquarie 54.5S, Orcadas, 60.7S, Signy 60.7S). Although these are administered together with the real Antarctic stations, they in fact are Oceanic.

    Even then, another 6 “Peninsula” stations are 100 km offshore on King George Island in the So Shetlands, and so even these are well out in the ocean currents, and not on the Peninsula or even locked to it with permanent ice.

    It’s small wonder that data from the “Peninsula” has a very different climate than the interior.

    See http://www.antarctica.ac.uk/met/READER/surface/stationpt.html

  22. Odonnell himself says there is no disagreement between the results of Steig in Nature and the results of O’Donnell for the last 30 years. The new Ding and others paper is based only on the last 30 years. Don’t confuse these two things.

    Also, Watts ought to read up a bit on Rossby waves. What the Ding paper is talking about has nothing much to do with the “the circumpolar vortex aka the southern polar jet steam”. A Rossby wave is basically any atmospheric wave that involves the coriolis force, as opposed to gravity waves. The meanders of the jet stream are Rossby waves, but not all Rossby waves are meanders of the jet stream. This is pretty elementary meteorology, so Watts ought to be a bit embarrassed. Perhaps he hasn’t read the paper before commenting on it?

    REPLY: Oh please. I know what Rossby waves are. My point is that weather transport via Rossby wave affects the peninsula more than the mainland, including those that transport some heat from the Pacific. The peninsula and WA clearly is where most of the Rossby wave trains impact, and it is the area of contention on “warming”. Your interpretation of O’Donnell et al seems selective.

    Regarding your criticism of not having read the latest Steig et al paper: If these scientists would in fact include the paper with their press release, we’d all be able to read it. As it stands, I cannot afford the journal subscriptions. I don’t have the glut of funding luxury or a government sugar daddy to pay for such things. Since you “seem” to have read the paper, are you part of UW? If so, please feel free to send a copy of the paper and to provide a copyright waver so we can all read it here online. Then we’ll have something to discuss in greater detail.

    The problem with so much of science today is the press release going out to be read by millions, but the actual science being kept behind a paywall. This lends itself to incomplete disclosure, and interpretation by the press release writer. Had it been available, I’d have used a figure or two. Had the press release bothered to include a figure, I’d have used that. They didn’t.

    In this case “The work was funded by the National Science Foundation.” so it should be public domain, but AFAIK, isn’t. At the link the PR exists at: http://www.washington.edu/news/articles/west-antarctic-warming-triggered-by-warmer-sea-surface-in-tropical-pacific

    I can find no link to the actual paper at UW in the public domain.

    – Anthony

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