Wobbles in the Barriers: Arctic Oscillation (4)

By: Dr. Ricky Rood , 4:22 PM GMT on October 14, 2013

Wobbles in the Barriers: Arctic Oscillation (4)

This is a continuation of my series on the Arctic Oscillation / North Atlantic Oscillation. Links to background material and previous entries are at the end.

In the last entry I suggested that if you were on a bridge overlooking a swiftly flowing creek then you would notice that twigs floating in the water did not move across the current. They are carried downstream along the edge of the current. The purpose of that comparison was to demonstrate how fast-moving, concentrated flows have the effect of isolating one side of the creek from the other. This is true in the creek, and it is also true about jet streams in the atmosphere.

One way to understand the Arctic Oscillation is to think of it as the variation of an atmospheric jet stream. For the Arctic Oscillation the jet stream of interest is the southern edge of vortex of air that circulates around the North Pole (see previous entry). Air inside the vortex often has characteristics different from air outside it. Intuitively for the Arctic, there is colder air on the side toward the pole. If you look at trace gases, like ozone, they are different across the edge of the vortex. The takeaway idea is that the edge of the vortex is a barrier. It’s not a perfect barrier, but the air on one side is largely separated from the air on the other side. In this blog, I describe the difference between a strong and a weak vortex – which is the same as the difference between the positive and negative phases of the Arctic Oscillation and the North Atlantic Oscillation.



Figure 1: This figure is from the point of view of someone looking down from above at the North Pole (NP). Compare this perspective to Figure 1 in previous blog. This represents a strong, circular vortex centered over the pole, which encloses cold air, represented as blue. The line surrounding the cold air is the jet stream or the edge of the vortex.

Figure 1 shows an idealized schematic of the North Pole as viewed from above. This is the strong vortex case, when there is exceptionally low pressure at the pole. Low pressure is associated with counterclockwise rotation in the Northern Hemisphere. This direction of rotation is called cyclonic. This strong vortex case is the positive phase of the Arctic Oscillation. During this phase, the vortex aligns strongly with the rotation of the Earth, and there are relatively few wobbles of the edge of the vortex – the jet stream. I drew on the figure two points, X and Y. In this case, the point X is hot and the point Y is cold. It is during this phase when it is relatively warm and moist over, for example, the eastern seaboard of the United States.

Figure 2 compares a strong vortex and a weak vortex. In both cases, the circulation around a central point is counterclockwise or cyclonic. However, in the weak vortex case, the vortex does not align as strongly with the rotation of the Earth and there are places where the edge of vortex extends southwards. The vortex appears displaced from the pole; it is not centered over the pole.



Figure 2: Examples of a strong, circular vortex and a weak, more wavy vortex. See text for a more complete description.

Whether the vortex is stronger or weaker is determined by the atmospheric pressure at the pole. In the winter, an important factor that determines the circulation is the cooling that occurs at polar latitudes during the polar night.

What determines the waviness or wobbles at the edge of this vortex? The structure at the edge of vortex is strongly influenced by several factors. These factors include the structure of the high-pressure centers that are over the oceans and continents to the south of jet stream. One could easily imagine a strong high-pressure center over, for example, Iceland, pushing northward at the edge of the vortex. This might push a lobe of air characteristic of the middle latitude Atlantic Ocean northward. Since the edge of the vortex is something of a barrier, this high-pressure system would distort the edge of the vortex and, perhaps, push the vortex off the pole. This would appear as a displacement of the vortex and its cold air over, for example, Russia. If the high grew and faded, then this would appear as wobbles of the vortex.

Other factors that influence the waviness at the edge of the vortex are the mountain ranges and the thermal contrast between the continents and the oceans. The impact of mountains is easy to understand. Returning to the creek comparison used above, the mountains are like a boulder in the stream. The water bulges around and over the boulder; the air in the atmosphere bulges around and over the mountain ranges. The Rocky Mountains in the western half of North America are perfect examples of where there are often wobbles in the atmospheric jet stream.



Figure 3: This figure is from the point of view of someone looking down from above at the North Pole (NP). This represents a weak, wavy, wobbly vortex displaced from the pole. The vortex encloses cold air, represented as blue. The line surrounding the cold air is the jet stream or the edge of the vortex. (definition of vortex)

Figure 3 shows an idealized schematic of the North Pole as viewed from above. This is the weak vortex case, when the low pressure at the pole is not as low as average and the pressure is much higher than the strong vortex case of Figure 1. This weak vortex case is the negative phase of the Arctic Oscillation. During this phase, the alignment of the vortex with the rotation of the Earth is less prominent, and there are wobbles of the edge of the vortex – the jet stream. In this case, the point X is cold and the point Y is hot. It is during this phase where it is relatively cool and dry (but potentially snowy) over, for example, the eastern part of the United States.

These figures help to explain the prominent signal of the Arctic Oscillation discussed in the earlier entries (specifically, this blog). That is, when the vortex is weak and wobbly, then there are excursions of colder air to the south and warmer air to the north. This appears as waviness and is an important pattern of variability - warm, cold, warm, cold.

The impact of the changes in the structure of edge of the vortex does not end with these persistent periods of regional warm and cold spells. The edge of the vortex or the jet stream is also important for steering storms. Minimally, therefore, these changes in the edge of the vortex are expected to change the characteristics of how storms move. Simply, if the edge of the vortex has large northward and southward extensions, then storms take a longer time to move, for example, across the United States from the Pacific to the Atlantic Oceans. In the positive phase of the Arctic Oscillation they just whip across. In the negative phase, the storms wander around a bit. A more complete discussion of this aspect of the role of the Arctic Oscillation will be in the next entry. (Note use of dramatic tension and the cliffhanger strategy of the serial.)

r

Previous entries:

Barriers in the Atmosphere
Behavior
Definitions and Some Background

August Arctic Oscillation presentation

CPC Climate Glossary “The Arctic Oscillation is a pattern in which atmospheric pressure at polar and middle latitudes fluctuates between negative and positive phases.”

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

Log In or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 257 - 207

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30Blog Index

Bye, guys. Keep up the good work. I'm off to finish up those Halloween costumes for the grandkids.
Member Since: Posts: Comments:
Quoting 250. yoboi:
Yes, well, I didn't think it was polite to say "shut up". I thought you could figure out the expression yourself. Over estimated you again. Sigh.
Member Since: Posts: Comments:
You tried that one over in Masters entry, do you really, really tink datun will fly here too?

LOL

When you "Master" the link button, we'll get back to yas.
Member Since: July 3, 2005 Posts: 449 Comments: 142001
<
Quoting 232. georgevandenberghe:



No she believes it's due to natural cycles. THe evidence is pretty clear she's wrong but she is not suggesting it's magic.
Believing "natural cycles" or "natural variability" is behind climate change without specifying which cycles, and what is driving those cycles, is indeed akin to believing in magic.

From Skeptical Science:

For a while now, I've considered climate change denial to be akin to superstition, which the Oxford Dictionaries site defines as "a widely held but irrational belief in supernatural influences." I mention this because when challenged, contrarians often claim that the climate changes we are witnessing are not man-made, but products of 'natural variabilit'. In this context, I find that 'natural variability' appears to be a synonym for supernatural influence'.

Why? Because they can’t explain it. Not just that: many seem to believe they are not obliged to do so, which is suspiciously convenient, and all too reminiscent of those who would claim they don't need to 'explain' God. In this, they share a view once expressed in a Guardian forum which, to this day, remains one of my favourite denialist non-sequiturs. When challenged, a poster calling himself Hamlet 4 insisted "I don’t need to prove climate change is caused by natural variability. It just is."
Member Since: November 8, 2009 Posts: 4 Comments: 15165
Kinda hard when he keeps logging out to Plus "Luvtogolf".

LOL
Member Since: July 3, 2005 Posts: 449 Comments: 142001
Quoting 239. yoboi:



If you have a different view with proven science to show..... there is censorship....
More baloney. More excuses. Look at all the stuff that's been posted here by Cochise and others. They aren't banned. Like I said, put it on your own blog. It's time to put up or ...
Member Since: Posts: Comments:
241.

wattsupwitdat, is NOT science, but thanx fore playing.

We have sum wunderground swag and a Mug as well.

Bye now!
Member Since: July 3, 2005 Posts: 449 Comments: 142001
What is funny Dr M's blog has two logging in and out to get well, Plus's.

I bet you cant name who?
Member Since: July 3, 2005 Posts: 449 Comments: 142001
Quoting 235. yoboi:




Not going to happen I keep getting banned......
Oh, baloney! If you're so worried about getting banned, post it on your own blog. You know how to do that. Weaseling out like this just destroys whatever credibility you have left - looks like you have no faith in the stuff you keep spouting off!

Edited: hmmm... If they banned you that fast, it must have been really bad. Maybe it's best you don't post it anywhere. We've already seen a couple of your - ahem - ill-considered arguments.
Member Since: Posts: Comments:
Does the global warming 'pause' mean what you think it means?



To quote Inigo Montoya from The Princess Bride, "You keep using that word. I do not think it means what you think it means."
In their study of media coverage of the 2013 Intergovernmental Panel on Climate Change (IPCC) report, Media Matters for America found that nearly half of print media stories discussed that the warming of global surface temperatures has slowed over the past 15 years. While this factoid is true, the question is, what does it mean?

Many popular climate myths share the trait of vagueness. For example, consider the argument that climate has changed naturally in the past. Well of course it has, but what does that tell us? It's akin to telling a fire investigator that fires have always happened naturally in the past. That would doubtless earn you a puzzled look from the investigator. Is the implication that because they have occurred naturally in the past, humans can't cause fires or climate change?

The same problem applies to the 'pause' (or 'hiatus' or better yet, 'speed bump') assertion. It's true that the warming of average global surface temperatures has slowed over the past 15 years, but what does that mean? One key piece of information that's usually omitted when discussing this subject is that the overall warming of the entire climate system has continued rapidly over the past 15 years, even faster than the 15 years before that.

nergy accumulation within distinct components of Earth’s climate system from 1971 to 2010. From the 2013 IPCC report.
The speed bump only applies to surface temperatures, which only represent about 2 percent of the overall warming of the global climate. Can you make out the tiny purple segment at the bottom of the above figure? That's the only part of the climate for which the warming has 'paused'. As the IPCC figure indicates, over 90 percent of global warming goes into heating the oceans, and it continues at a rapid pace, equivalent to 4 Hiroshima atomic bomb detonations per second.

More at The Guardian ...
Member Since: June 27, 2012 Posts: 0 Comments: 4598
C'mon guys. Let's not dismiss ncstorm until she has responded to Daisyworld. Facing the truth of climate change and its consequences is not easy - as we all know.
Member Since: Posts: Comments:
Quoting 227. Neapolitan:
No, she does "believe" in climate change, but she's of the opinion that it's happening via magic... ;-)



No she believes it's due to natural cycles. THe evidence is pretty clear she's wrong but she is not suggesting it's magic.
Member Since: Posts: Comments:
From RationalWiki, a little background on Marc Morano, as a warmup for yoboi's promised bombshell this morning: Link

Marc Morano is a wingnut propagandist and global warming denier (his fans call him a "climate realist"). He kicked off his career by learning the tricks of the trade as a producer on Rush Limbaugh's show in the early '90s. He then went on to work for L. Brent Bozell's Media Research Center.

In 2004, he was one of the first "reporters" to hype the John Kerry swiftboating "story." In 2006, preeminent denier and wingnut Jim Inhofe hired Morano to be his "Director of Communications." Morano's position got him into a number of climate conferences and policy hearings. He also put out a bogus report about 700+ number of scientists who "disagreed" with the consensus (a la Oregon Petition). Some scientists called for his resignation due to the number of distortions and lies about their work he promulgated. In 2009, Morano left Inhofe and became the proprietor of the website "Climate Depot." Climate Depot is sponsored by the Committee for a Constructive Tomorrow, an Exxon funded think tank.[1] Supposedly, he exposes the "lies" of the "warmists" and "scientific McCarthy-ites" (oh the irony!) who do research in that inconvenient thing called science. The site is really more of a denialist-style Drudge Report that links to whatever nonsense it can find.
Member Since: Posts: Comments:
Quoting 227. Neapolitan:
No, she does "believe" in climate change, but she's of the opinion that it's happening via magic... ;-)


It's the "Fallacy of Immaculate Causaton"

h/t to Paul Krugman
Member Since: June 27, 2012 Posts: 0 Comments: 4598
Quoting 226. ScottLincoln:

You don't believe in climate change, but it is due to natural cycles? ...What?
No, she does "believe" in climate change, but she's of the opinion that it's happening via magic... ;-)
Member Since: November 8, 2009 Posts: 4 Comments: 15165
Quoting 208. ncstorm:
Statement:
I also want to state that I do believe in climate change but that its earth natural cycles and we have seen these events before..


You don't believe in climate change, but it is due to natural cycles? ...What?
Member Since: September 28, 2002 Posts: 5 Comments: 3529
Without Plants, Earth Would Cook Under Billions of Tons of Additional Carbon

Enhanced growth of Earth's leafy greens during the 20th century has significantly slowed the planet's transition to being red-hot, according to the first study to specify the extent to which plants have prevented climate change since pre-industrial times. Researchers based at Princeton University found that land ecosystems have kept the planet cooler by absorbing billions of tons of carbon, especially during the past 60 years.

The planet's land-based carbon "sink" -- or carbon-storage capacity -- has kept 186 billion to 192 billion tons of carbon out of the atmosphere since the mid-20th century, the researchers report in the Proceedings of the National Academy of Sciences. From the 1860s to the 1950s, land use by humans was a substantial source of the carbon entering the atmosphere because of deforestation and logging. After the 1950s, however, humans began to use land differently, such as by restoring forests and adopting agriculture that, while larger scale, is higher yield. At the same time, industries and automobiles continued to steadily emit carbon dioxide that contributed to a botanical boom. Although a greenhouse gas and pollutant, carbon dioxide also is a plant nutrient.

Had Earth's terrestrial ecosystems remained a carbon source they would have instead generated 65 billion to 82 billion tons of carbon in addition to the carbon that it would not have absorbed, the researchers found. That means a total of 251 billion to 274 billion additional tons of carbon would currently be in the atmosphere. That much carbon would have pushed the atmosphere's current carbon dioxide concentration to 485 parts-per-million (ppm), the researchers report -- well past the scientifically accepted threshold of 450 (ppm) at which Earth's climate could drastically and irreversibly change. The current concentration is 400 ppm.

Although the researchers saw a strong historical influence of carbon fertilization in carbon absorption, that exchange does have its limits, Saleska said. If carbon dioxide levels in the atmosphere continue rising, more vegetation would be needed to maintain the size of the carbon sink Shevliakova and her colleagues reported.

"There is surely some limit to how long increasing carbon dioxide can continue to promote plant growth that absorbs carbon dioxide," Saleska said. "Carbon dioxide is food for plants, and putting more food out there stimulates them to 'eat' more. However, just like humans, eventually they get full and putting more food out doesn't stimulate more eating."


sciencedaily.com
Member Since: Posts: Comments:
One last thought on deniers
Member Since: June 27, 2012 Posts: 0 Comments: 4598
Quoting 220. yoboi:


well I am turning in and I have been holding the bombshell that will show what is going on tomm get some rest ya will need it.... as always enjoyed the convo...

Edit: Marc Morano taught me a class for 2 weeks...I am ready round up the agw gang.....


Don't let it explode in your face.
Member Since: Posts: Comments:
Quoting 217. Birthmark:

You are mistaken. No one can change the data. Nice try, though.

But if you don't like WfT, you can always go here. You'll have to download the graphs and then upload them to post them here, and you can only display one data set per graph, but there's the added advantage of having the trend numerically displayed with 2-sigma error.


I'll totally bring my laptop up to you so you can use my copy of SPSS and we can crunch some numbers over Loatian coffee. Sounds like a fun 15 minutes while the graphs run. :)
Member Since: Posts: Comments:
Quoting 213. Daisyworld:


The fingerprint of humans on the rising CO2 is very clear, and it's 50-100 times that of natural volcanic origin. The evidence is:

(1) Measurements of the CO2 output from both volcanoes and fossil fuel burning show that fossil fuel burning far exceeds that of present-day volcanoes. (Link)

(2) The increase in atmospheric CO2 is proportional to a decrease in atmospheric O2, which shows that the CO2 is being created from combustion. (Link)

(3) The carbon isotope signature of the CO2 shows an increase in 12C, which comes from living organisms. There's NO relevant increase in 13C, which comes from melting rocks (volcanoes), and NO increase in 14C, which comes from recently dead living organisms. Therefore, the carbon in CO2 is coming from once living organisms that have been dead for a very long time… aka fossil fuels. (Link)

I've posted it before, and I'll post it again. Dr. Richard Alley says it best:



I'll try to watch this tomorrow and let you know what I think..
Member Since: August 19, 2006 Posts: 13 Comments: 18083
Quoting 208. ncstorm:
[...]

Statement:
I also want to state that I do believe in climate change but that its earth natural cycles and we have seen these events before..



The fingerprint of humans on the rising CO2 is very clear, and it's 50-100 times that of natural volcanic origin. The evidence is:

(1) Measurements of the CO2 output from both volcanoes and fossil fuel burning show that fossil fuel burning far exceeds that of present-day volcanoes. (Link)

(2) The increase in atmospheric CO2 is proportional to a decrease in atmospheric O2, which shows that the CO2 is being created from combustion. (Link)

(3) The carbon isotope signature of the CO2 shows an increase in 12C, which comes from living organisms. There's NO relevant increase in 13C, which comes from melting rocks (volcanoes), and NO increase in 14C, which comes from recently dead living organisms. Therefore, the carbon in CO2 is coming from once living organisms that have been dead for a very long time… aka fossil fuels. (Link)

I've posted it before, and I'll post it again. Dr. Richard Alley says it best:

Member Since: Posts: Comments:
This is my second time posting in Rood's blog so please be kind..

Questions??

So If I refute a claim in here with a graph and you then in turn refute my claim with another graph, who would be right?

Are there any opposing website to GW consider legit to your thinking because I dont want to even post something that will immediately get called a lie even though it will have truth to it?

Statement:
I also want to state that I do believe in climate change but that its earth natural cycles and we have seen these events before..

Member Since: August 19, 2006 Posts: 13 Comments: 18083

Viewing: 257 - 207

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30Blog Index

Top of Page
Ad Blocker Enabled

Dr. Ricky Rood's Climate Change Blog

About RickyRood

I'm a professor at U Michigan and lead a course on climate change problem solving. These articles often come from and contribute to the course.

RickyRood's Recent Photos

Clouds in the lee of the Rockies at sunset.
Clouds in the lee of the Rockies at sunset.
Clouds in the lee of the Rockies at sunset.
Clouds in the lee of the Rockies at sunset.