# 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.”

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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##### 154. Daisyworld
 Quoting 151. Birthmark:Quoting 147. tramp96: I think you are out of your element.Do you? Good for you! lolSo, Birthmark. You're driving a Honda these days? :-P
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##### 153. JohnLonergan
 Quoting 114. FLwolverine:Do you even understand what that means? Bet you can't explain it!I think he stole it from Johnny Cochran.
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##### 152. Patrap
 The Password is..."Cognitive Dissonance"Cognitive dissonance is the distressing mental state that people feel when they "find themselves doing things that don't fit with what they know, or having opinions that do not fit with other opinions they hold."
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##### 148. Daisyworld
 Quoting 143. tramp96:And moreLinkOh dear. Tramp96, that one has been addressed, refuted, and debunked: LinkI'd rather stick to the CBS article...
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##### 142. Daisyworld
 Quoting 141. tramp96:The article was signed by scientists. CBS is hardly a scientific news organization. They are barely news just ask Dan Rather.Just in case you hadn't noticed, the CBS article had a link to the actual scientific paper that inspired the article. That's more than you'll get from FoxNews.Most media organizations fail in their responsibility to effectively communicate published science to the general public. If they actually quote a peer-reviewed science paper in context, then you probably have a decent news article on your hands.
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##### 140. Daisyworld
 And now for some actual climate news...Study: Climate change will significantly impact ocean health by 2100by Danielle Elliot | CBS News | October 16, 2013New research shows that human impact on the climate will heavily influence marine habitats by 2100, supporting a study earlier this month that showed coral reefs could be extinct by 2050. Climate change triggered by greenhouse gas emissions will influence every corner of the world ocean by that time, the researchers say. They predict that the changes will impact the 470-870 million people who depend on the oceans for their livelihoods."When you look at the world ocean, there are few places that will be free of changes; most will suffer the simultaneous effects of warming, acidification, and reductions in oxygen and productivity," lead author Camilo Mora said in a press release. Mora is an assistant professor in the Department of Geography in the College of Social Sciences at the University of Hawaii at Manoa.Published Oct. 15 in the open-source journal PLOS Biology, Mora's latest research looked at co-occurrence of changes in temperature, pH, oxygen and primary productivity in the 32 marine environments. They also measured local populations' dependency on the ocean for food, commerce and social adaptability in order to estimate how vulnerable these populations are to change."Other studies have looked at small-scale impacts, but this is the first time that we've been able to look the entire world ocean and how co-occurring stressors will differentially impact the earth's diverse habitats and people," said co-author Andrew Thurber, a postdoctoral fellow at Oregon State University. "The real power is in the quantitative, predictive approach using IPCC climate models that allow us to see how much it will all change, and also how confident we can be in our estimates."The results show that global averages for the upper layer of the ocean will change the most: the temperature will increase between 1.2 and 2.6 degrees Celsius, dissolved oxygen will decrease by 2 to 4 percent of the current measurements, and pH will decline by .15 to .31."The consequences of these co-occurring changes are massive--everything from species survival, to abundance, to range size, to body size, to species richness, to ecosystem functioning are affected by changes in ocean biogeochemistry," said Mora.These changes will affect coral reefs, seagrass beds and other shallow habitats. The seafloor will see similar changes in dissolved oxygen but less severe temperature and pH changes.While less severe than the impacts on shallower areas, these changes will have long-term affects on overall ocean health."The deep-sea floor covers most of the Earth's surface and provides a whole host of important ecosystem services including carbon sequestration in seafloor sediments, buffering of ocean acidity, and providing an enormous reservoir of biodiversity," said co-author Craig Smith."Nonetheless, very little attention has been paid to modeling the effects of climate change on these truly vast ecosystems. Perhaps not surprisingly, many deep seafloor ecosystems appear susceptible to the effects of climate warming over the next century.""The impacts of climate change will be felt from the ocean surface to the seafloor. It is truly scary to consider how vast these impacts will be," added co-author Andrew K. Sweetman. "This is one legacy that we as humans should not be allowed to ignore."© 2013 CBS Interactive Inc. All Rights Reserved.
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##### 137. Patrap
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##### 131. Naga5000
 Quoting 130. tramp96:The article i posted a couple of days ago was from the WSJ hardly an extreme right wing blog.On the other side of things how are you?Well the WSJ did take a but of a turn after News Corp bought it, but that for another time, and I do apologize for not responding in a timely fashion to your WU mail. I've been busy and tired...not a good combination to have a good discussion. I will get back to you tomorrow after a good night's sleep.
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##### 128. Naga5000
 Quoting 117. tramp96:The refreshing truthLinkThe American Thinker is not so much a thinker...you're letting political belief affect how you view science.The only dissenting voice in climate change science comes from the extreme right in the form of blogs do you think that's a coincidence?
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##### 127. Neapolitan
 Quoting 104. MisterPerfect:My Turn: Hockey stick comparison – Al Gore vs. Ben BernankeBy Jeff Ridgel, Tahoe Daily Tribune - October 15, 2013Al Gore made himself a political name, and a personal fortune, by widely disseminating hyperbole on manmade global warming. His famous hockey stick chart depicting exponential growth of global temperatures, directly related to emissions of man-generated gases, has had major political and economic repercussions.As a firm believer in the scientific method, a former instructor of statistics, and one that has used statistical modeling extensively for military applications in radar design, I approached this topic with healthy skepticism. I went back to the original data samples and evaluated the original mathematical modeling.Unfortunately, different than the conclusions reached by the International Commission on Climate Change, and in alarming disagreement with the economic impact resulting from the political fallout from this statistical modeling, I believe that politics and money drove desired conclusions not founded in the data.Given the amount of public opinion that has been persuaded along the lines of global warming created by man’s actions, stating a contrary opinion is not done lightly.However, fundamental flaws in the research, such as establishing a deterministic causal relationship indicating high carbon dioxide levels in the atmosphere indeed led to higher global temperatures, and not the other way around, was not done. And whereas one would not doubt the irrefutable evidence that global warming is indeed occurring with Arctic ice melt at record highs, determining a causal relationship by man-made evidence being more than a trivial factor has not been established.Other factors, for example, well known periodic sun activity, appear to be much more significant contributors and well documented in core sample data. And although I am a conservationist, and believe firmly in pursuing clean air and water for our environment and health, the economic impact brought on by EPA and State mandates are direct contributors to our debt issues today. Which brings up our second hockey stick, Ben Bernanke’s. As opposed to global warming, the national debt is not based on a politicized statistical model. It is real and increasing exponentially.The national debt slowly increased up through 2005. Starting in 2006, under Bernanke’s lead as Fed Chairman fulfilling the progressive spending surge of Barack Obama and creative “Quantitative Easing” stimulus plan, the national debt has indeed taken on the look of Al Gore’s hockey stick.As indicated above, there is a direct relationship between Al Gore’s hockey stick and Ben Bernanke’s hockey stick. I finally got what all the hoopla is about. Thanks Al.http://www.tahoedailytribune.com/northshore/85224 04-113/hockey-stick-global-bernankeGee, Mr. P, you sure do seem to have a heavy attraction for Al Gore. I am friends with a guy who knows his family; want me to try to set you up with a date?
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##### 119. Patrap
 Its not a real pause in Govt, its been a Hoax dreamed up by well, non Coffee drinkers.There's a graph to prove it on Anthony Watts site.
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##### 116. Daisyworld
 Quoting 111. yoboi:If you can't explain the pause.......Can you really know the cause??????You know, you're right. I can't explain this pause in government services. I had thought that it was because a fundamentalist minority in congress were overly-fervent about defunding a law passed years ago and upheld by the supreme court. However, in light of your comment, I'm so unsure of myself now that this pause in services could last forever...
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##### 114. FLwolverine
 Quoting 111. yoboi:If you can't explain the pause.......Can you really know the cause??????Do you even understand what that means? Bet you can't explain it!
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##### 113. Astrometeor
 Quoting 106. Cochise111:I hate to tell you this, but you're wasting your energy attempting to convey logic. These people are part of the liberal order, which, in my humble opinion, and that of learned psychiatrists, is a mental disorder. No matter how much evidence is presented, they continue to ignore it and follow their new religion. They won't even admit that global temperatures have not changed in over fifteen years. I don't believe that the average global temperature is calculable, but even with their biased, adjusted, corrupted, tweaked, and otherwise-false global temperatures, they still can't show global warming. The almost 100 models they use can't forecast past much less future temperatures, yet they want the world to believe they can predict climate differences decades into the future. It would be laughable if it weren't so depressing to the world economies.I hate to tell you this, but we aren't discussing religion here, we are discussing science.And, I don't think everyone here falls into "liberal order". I sure don't. And, that's me assuming the political definition most Americans recognize. But that doesn't stop me from understanding basic physics principles and agreeing with the facts that so many kind and generous folks here are willing to present.
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##### 110. FLwolverine
 Quoting 107. Daisyworld:Like MrPerfect, you post lots of lies, but offer no actual scientific data to support your position. Why should anyone listen to you?I wonder if Cochise has the same crush on Al Gore that MrPerfect does.
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##### 109. Daisyworld
 Agreed. That was one of the largest cases of confusing double-talk I've ever read:"fundamental flaws in the research, such as establishing a deterministic causal relationship indicating high carbon dioxide levels in the atmosphere indeed led to higher global temperatures, and not the other way around, was not done"This statement makes no logical sense. To me, it was like reading "I'm sure that you don't want to not reply to this comment which is not a sentence."That whole article that MisterPerfect posted was a classic case of deliberately confusing the argument, but with the author insisting that their logic is airtight and that anyone who disagrees with them is either too dumb or too fanatical to follow along. AKA, propaganda technique #8 from Dr. Cynthia Boaz's 14 propaganda techniques that FoxNews uses to brainwash Americans.
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##### 108. JohnLonergan
 Quoting 105. Daisyworld:That quote is a perfect example of weapons grade stupid, but the source is Bob Carter. All you need to know about Bob Carter:Key Quotes"The first thing to be clear about is that carbon dioxide is not a pollutant." [5]
Member Since: December 31, 1969 Posts: Comments:
##### 107. Daisyworld
 Quoting 106. Cochise111:I hate to tell you this, but you're wasting your energy attempting to convey logic. These people are part of the liberal order, which, in my humble opinion, and that of learned psychiatrists, is a mental disorder. No matter how much evidence is presented, they continue to ignore it and follow their new religion. They won't even admit that global temperatures have not changed in over fifteen years. I don't believe that the average global temperature is calculable, but even with their biased, adjusted, corrupted, tweaked, and otherwise-false global temperatures, they still can't show global warming. The almost 100 models they use can't forecast past much less future temperatures, yet they want the world to believe they can predict climate differences decades into the future. It would be laughable if it weren't so depressing to the world economies.Like MrPerfect, you post lots of lies, but offer no actual scientific data to support your position. Why should anyone listen to you?
Member Since: Posts: Comments:

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