Introducing The New WUWT Northern Polar Vortex Page – With Explanation and Observations

Robert Clemenzi says: January 18, 2014 at 2:14 pm
The descriptions above talk of the vortex causing cold air to sink and provide more cold air to the pole. The implication is that this some how makes the pole colder. I don’t understand how this is possible. In general, the stratosphere gets warmer with increasing height, even over the poles. As a result, the sinking air should make the poles warmer.
You are correct that “In general, the stratosphere gets warmer with increasing height”;
[caption id="" align="alignnone" width="578"] PhysicalGeography.net – Click the pic to view at source[/caption]
however, “the polar vortex extends from the tropopause (the dividing line between the stratosphere and troposphere) through the stratosphere and into the mesosphere (above 50 km). Low values of ozone and cold temperatures are associated with the air inside the vortex.” NASA
If you review the descending Temperature Analyses in my recent article A Sober Look At The Northern Polar Vortex, it is apparent that air within the Polar Vortex is much colder that the air around it, e.g.:
Starting at 10 hPa/mb – Approximately 31,000 meters (101,700 feet) here we have a Height Analysis showing the low pressure area;
[caption id="" align="alignnone" width="578"] NOAA – National Weather Service – Climate Prediction Center – Click the pic to view at source[/caption]
a Temperature Analysis showing the cold area;
[caption id="" align="alignnone" width="578"] NOAA – National Weather Service – Climate Prediction Center – Click the pic to view at source[/caption]
and Ozone Mixing Ratio map showing the “Ozone Hole” within it:
[caption id="" align="alignnone" width="578"] NOAA – National Weather Service – Climate Prediction Center – Click the pic to view at source[/caption]
In addition, there is the consideration of “potential temperature”. Basically, this means that air gets warmer as it moves toward the surface because of the change in pressure – about 9.8K per kilometer. As a result, air from the mesosphere (0°C at about 50km), if moved to the surface, would be over 450°C!
But there isn’t the same “change in pressure” within the vortex, as the walls of the vortex maintain the low pressure as the cold air descends. However, when the vortex breaks up, the pressures equalize and we get a Sudden Stratospheric Warming, i.e.:
“A stratospheric sudden warming is perhaps one of the most radical changes of weather that is observed on our planet. Within the space of a week, North Pole temperatures can increase by more than 50 K (90°F). For example, on 17 January 2009 the temperature at the North Pole near 30 km was about 200 K. Over a 5-day period, the temperature increased to 260 K (a change of 60 K or 108°F).
These stratospheric sudden warmings are caused by atmospheric waves that originate in the troposphere. The waves are forced by the large-scale mountain systems of the northern hemisphere and the land-sea contrasts between the continents and oceans. The waves are also characterized by their very large scales, typically referred to as planetary-scale waves. The stratospheric wind structure filters the smaller scale waves, only allowing the planetary waves to propagate into the stratosphere. As the waves move upward into the stratosphere they have two effects: first they will often push the polar vortex away from the North Pole—bringing warmer midlatitude air poleward, and second, they produce a downward motion field that also warms the polar region.” NASA

Daniel Vogler says: January 18, 2014 at 1:24 pm
the Solar influence on the Stratosphere is linked to the type of QBO phase, a decent correlation of SSWs and the QBO phase and solar Flux
http://f1.nwstatic.co.uk/forum/uploads/monthly_01_2014/post-10577-0-14746500-1389168133.jpg
I actually argued the solar – QBO link with Leif a few years ago, but didn’t make any headway.
“The Influence of the Solar Cycle and QBO on the Late-Winter Stratospheric Polar Vortex”
Camp et al. 2006:
“A statistical analysis of 51 years of NCEP–NCAR reanalysis data is conducted to isolate the separate effects of the 11-yr solar cycle (SC) and the equatorial quasi-biennial oscillation (QBO) on the Northern Hemisphere (NH) stratosphere in late winter (February–March). In a four-group [SC maximum (SC-max) versus minimum (SC-min) and east-phase versus west-phase QBO] linear discriminant analysis, the state of the westerly phase QBO (wQBO) during SC-min emerges as a distinct least-perturbed (and coldest) state of the stratospheric polar vortex, statistically well separated from the other perturbed states. Relative to this least-perturbed state, the SC-max and easterly QBO (eQBO) each independently provides perturbation and warming as does the combined perturbation of the SC-max–eQBO. All of these results (except the eQBO perturbation) are significant at the 95% confidence level as confirmed by Monte Carlo tests; the eQBO perturbation is marginally significant at the 90% level. This observational result suggests a conceptual change in understanding the interaction between solar cycle and QBO influences: while previous results imply a more substantial interaction, even to the extent that the warming due to SC-max is reversed to cooling by the eQBO, results suggest that the SC-max and eQBO separately warm the polar stratosphere from the least-perturbed state. While previous authors emphasize the importance of segregating the data according to the phase of the QBO, here the same polar warming by the solar cycle is found regardless of the phase of the QBO.
The polar temperature is positively correlated with the SC, with a statistically significant zonal mean warming of approximately 4.6 K in the 10–50-hPa layer in the mean and 7.2 K from peak to peak. This magnitude of the warming in winter is too large to be explainable by UV radiation alone. The evidence seems to suggest that the polar warming in NH late winter during SC-max is due to the occurrence of sudden stratospheric warmings (SSWs), as noted previously by other authors. This hypothesis is circumstantially substantiated here by the similarity between the meridional pattern and timing of the warming and cooling observed during the SC-max and the known pattern and timing of SSWs, which has the form of large warming over the pole and small cooling over the midlatitudes during mid- and late winter. The eQBO is also known to precondition the polar vortex for the onset of SSWs, and it has been pointed out by previous authors that SSWs can occur during eQBO at all stages of the solar cycle. The additional perturbation due to SC-max does not double the frequency of occurrence of SSWs induced by the eQBO. This explains why the SC-max/eQBO years are not statistically warmer than either the SC-max/wQBO or SC minimum/eQBO years. The difference between two perturbed (warm) states (e.g., SC-max/eQBO versus SC-min/eQBO or SC-max/eQBO versus SC-max/wQBO), is small (about 0.3–0.4 K) and not statistically significant. It is this small difference between perturbed states, both warmer than the least-perturbed state, that in the past has been interpreted either as a reversal of SC-induced warming or as a reversal of QBO-induced warming.”
“The mechanism of QBO’s interaction with the polar stratosphere is better understood, and yet many of the reported observational results have not been explained.Holton and Tan (1980, 1982) discovered what is now called the Holton – Tan effect. They found that in composites, according to the phase of the equatorial QBO at 50 hPa, the polar winter temperature is warmer and the polar vortex is more perturbed by planetary waves when the equatorial QBO is in its easterly phase than in its westerly phase. For a possible mechanism, they cited the work of Tung and Lindzen (1979a) on the effect of the position of the zero-wind line on the stationary planetary waves: As the zero-wind line moves more poleward during eQBO, the westerly waveguide for stationary waves is narrowed and located more poleward. This tends to focus the planetary waves more poleward, making the polar vortex more disturbed and hence warmer. Our understanding of wave – mean flow interaction in the stratosphere has progressed considerably since the late 1970s. Instead of the quasi-linear picture of wave – mean interaction in which the zero-wind line plays a crucial role, it is now understood that the dynamics is highly nonlinear in the stratosphere, and planetary waves break in surf zones (McIntyre and Palmer 1984). Nevertheless, the planetary waves do tend to break more poleward during the QBO easterly phase than during the westerly phase when the waveguide is wider and the wave flux is directed more equatorward. Holton and Tan (1980) divided the winter into early winter (November – December) and late winter (January – March). They found, using 16 years of data, that in early winter wavenumber-1 amplitude at 50 hPa is about 40% greater in eQBO than in wQBO, at the 99% confidence level in a Student’s t test. This positive result was later questioned by Naito and Hirota (1997, hereafter NH97) who found that the Holton – Tan result for 1962/63 – 1977/78 failed to hold in the longer record up to 1993/94. NH97 conjectured that the difference found by Holton and Tan was due to the solar cycle because the period used by them happens to contain two solar minima and one maximum. They therefore suggested that Holton and Tan’s result could not be valid in general, it being applicable only to periods with more solar minima than maxima. Gray et al.(2001)’s findings echo these: For the shorter 26-yr period of 1964 – 90, with a bias toward the solar minimum, the correlation between January – February North Polartemperature in the lower stratosphere with the equatorial QBO wind is 0.4 (the negative sign meaning that the pole is warmer during easterly QBO years), but reduces to 0.25 for the 44 winters from 1955 to 1999, including four full solar cycles. Holton and Tan (1980) also found that during late winter the behavior of wave-number 2 was unexpectedly opposite, being about 60% stronger, in the composite mean, during the wQBO than in the eQBO at 96% confidence level. However, when four more years were added to the sample, they found that the significance level dropped to about 90%.”
Conclusions:
“1) There is a very well separated state of the polar stratosphere, which occurs during the confluence of a solar cycle minimum and westerly QBO; we denote this state as the “
least-perturbed state.” This state is statistically distinguished from all other (perturbed) states at more than the 99% confidence level.
2) Relative to this least-perturbed state, a solar maximum warms the pole by a mean of approximately 4.6 K (7.2 K peak to peak) during the wQBO and also during the eQBO; both results are statistically significant at more than the 95% confidence level. The statistically significant discriminant spatial patterns of the warming take the form of the structure
associated with sudden stratospheric warmings.
3) The above result shows that the solar cycle warms the polar stratosphere by the same amount regardless of the phase of the QBO. It then follows that the stratification of the data according to the phase of the QBO is not necessary in order to see the SC response, except for its necessity in defining the reference state.
4) Relative to the least-perturbed state, easterly QBO also warms the pole by approximately 4 K but at a lower confidence level of 90%. This lowered significance may be due to the fact that the preconditioning of the SSW by a QBO may depend on the equatorial wind at several height layers (Gray et al. 2001; Gray 2003). The spatial structure is also similar to that of the SSW.
5) Statistically significant results are obtained when perturbations are measured relative to the least-perturbed state. Previous confusion over possible reversals of solar cycle warming or of the Holton – Tan QBO mechanism are now seen to arise from the comparison of one perturbed state with another perturbed state. These differences are not statistically significant due to the similarity of each of the perturbations. In Fig. 9, the differences between perturbed states are denoted by dashed arrows. Two group LDAs between the perturbed states (not
shown) show that there is an approximately 0.4-K warming from SC-min/eQBO to SC-max/eQBO (i.e., SC perturbation during eQBO) and an approximately 0.3-K cooling from SC-max/wQBO to SC-max/eQBO (i.e., QBO perturbation during the SC-max). The latter result (the small cooling) has been interpreted as a reversal of the Holton – Tan mechanism; however, both of these results have very low statistical significances and so the signs of the
warming should not be taken seriously.”
“The Influence of the Solar Cycle and QBO on the Late-Winter Stratospheric Polar Vortex, Lu et al.
“SIGNALS OF SOLAR WIND DYNAMIC PRESSURE IN THE NORTHERN ANNULAR MODE AND THE EQUATORIAL STRATOSPHERIC QUASI-BIENNIAL OSCILLATION”
They “report statistically measurable responses of the Northern Annular Mode (NAM) and the equatorial stratospheric Quasi-biennial Oscillation (QBO) to solar wind dynamic pressure. When December to January solar wind dynamic pressure is high, the Northern Hemispheric (NH) circulation response is marked by a stronger polar vortex and weaker sub-tropical jet in the upper to middle stratosphere. As the winter progresses, the Arctic becomes colder and the jet anomalies shift poleward and downward. In spring, the polar stratosphere becomes anomalously warmer. At solar maxima, significant positive correlations are found between December to January solar wind dynamic pressure and the mid- to late winter NAM all the way from the surface to 20 hPa, implying a strengthened polar vortex, reduced Brewer-Dobson circulation and enhanced stratosphere-troposphere coupling. The combined effect of high solar UV irradiance and high solar wind dynamic pressure in the NH mid- to late winter is enhanced westerlies in the extratropics and weaker westerlies in the subtropics, indicating that more planetary waves are refracted towards the equator. At solar minima, there is no correlation in the NH winter but negative correlations between December to January solar wind dynamic pressure and the NAM are found only in the stratosphere during spring. Statistical evidence of a possible modulation of the equatorial stratospheric Quasi-biennial Oscillation (QBO) by the solar wind dynamic pressure is also provided. When solar wind dynamic pressure is high, the QBO at 30-70 hPa is found to be preferably more easterly during July to October. These lower stratospheric easterly anomalies are primarily linked to the high frequency component of solar wind dynamic pressure with periods shorter than 3-years. In annually and seasonally aggregated daily averages, the signature of solar wind dynamic pressure in the equatorial zonal wind is characterized by a vertical three-cell anomaly pattern with westerly anomalies both in the troposphere and the upper stratosphere and easterly anomalies in the lower stratosphere. This anomalous behavior in tropical winds is accompanied by a downward propagation of positive temperature anomalies from the upper stratosphere to the lower stratosphere over a period of a year. These results suggest that the solar wind dynamic pressure exerts a seasonal change of the tropical upwelling which results in a systemic modulation of the annual cycle in the lower stratospheric temperature, which in turn affects the QBO during Austral late winter and spring. These results suggest possible multiple solar inputs. Their combined effect in the stratosphere may cause refraction/redistribution of upward wave propagation and result in projecting the solar wind signals onto the NAM and the QBO. The route by which the effects of solar wind forcing might propagate to the lower atmosphere is yet to be understood.”
“Possible solar wind effect on the northern annular mode and northern hemispheric circulation during winter and spring, Lu et al.
Found “statistically measurable responses of atmospheric circulation to solar wind dynamic pressure are found in the Northern Hemisphere (NH) zonal-mean zonal wind and temperature, and on the Northern Annular Mode (NAM) in winter and spring. When December to January solar wind dynamic pressure (P sw DJ) is high, the circulation response is marked by a stronger polar vortex and weaker sub-tropical jet in the upper to middle stratosphere. As the winter progresses, the Arctic becomes colder and the jet anomalies shift poleward and downward. In spring, the polar stratosphere becomes anomalously warmer. At solar maxima, significant positive correlations are found between P swDJ and the middle to late winter NAM all the way from the surface to 20 hPa, implying a strengthened polar vortex, reduced Brewer–Dobson circulation and enhanced stratosphere-troposphere coupling. The combined effect of high solar UV irradiance and high solar wind dynamic pressure in the NH middle to late winter is enhanced westerlies in the extratropics and weaker westerlies in the subtropics, indicating that more planetary waves are refracted toward the equator. At solar minima, there is no correlation in the NH winter but negative correlations between P swDJ and the NAM are found only in the stratosphere during spring. These results suggest possible multiple solar inputs that may cause refraction/redistribution of upward wave propagation and result in projecting the solar wind signals onto the NAM. The route by which the effects of solar wind forcing might propagate to the lower atmosphere is yet to be understood.”
There appear to be correlations between solar wind dynamic pressure and the NAM and QBO. However, Leif argued that there is no known mechanism whereby ”the effects of solar wind forcing might propagate to the lower atmosphere”. At this point I would argue that Polar Vortex Perturbation is at least plausible.

Chuck L says: January 18, 2014 at 12:08 pm
It is also helpful to note that:Planetary Vorticity “is zero at equator, is maximum at pole (one revolution per day)” and “is always positive (cyclonic)”. Lyndon State College Atmospheric Sciences
[caption id="" align="alignnone" width="500"] Lyndon State College Atmospheric Sciences – Click the pic to view at source[/caption]

Gunga Din says: January 19, 2014 at 1:40 pm
1. “Polar Vortex” is nothing new.
Correct, the book Living Age from 1853 references the Polar Vortex and Google Scholar brings back 16,100 citations for Polar Vortex”:
http://scholar.google.com/scholar?hl=en&q=%22polar+vortex%22&btnG=&as_sdt=1%2C31&as_sdtp=
2. “Polar Vortex” has not been commonly used to describe winter weather events to the public.
Correct, prior to 2014 the Google Trend for “Polar Vortex” is almost dead:
http://www.google.com/trends/explore#q=polar%20vortex&date=1%2F2004%20121m&cmpt=q
However, it is important to note this January 25, 2011, New York Times article Cold Jumps Arctic ‘Fence,’ Stoking Winter’s Fury and associated NYT blog post Frigid Winters and the Polar Vortex, which both reference the Polar Vortex.
3. “Polar Vortex” is now being used to make what is a normal winter weather event seem “abnormal” or “weird” to the public?
Correct, though a lot of this can be attributed to sensationalism versus an organized disinformation campaign, i.e.:

John Holdren, Jennifer Francis and numerous others are currently disingenuously trying to use the Polar Vortex to explain why warming causes cooling. However, I encourage them, as the warming causes cooling meme is a sure fire loser. All but a brainwashed lemming can see that John, Jennifer and company are contorting themselves to try to cram polar breakouts and freezing temps into the rapidly crumbling Catastrophic Anthropogenic Global Warming Narrative. One does not need to understand the intricacies of Polar Vorticity in order to know when one is being lied to. I expect that when we see the next round of survey results, the Polar Vortex and Ship of Fools memes will result in “Global warming denial” hitting new highs, i.e. Global warming denial hits a six-year high:
“The percentage of Americans who believe global warming is human-caused has also declined, and now stands at 47 percent, a decrease of 7 percent since 2012.”
“The obvious question is, what happened over the last year to produce more climate denial?
According to both Anthony Leiserowitz of Yale and Ed Maibach of George Mason, the leaders of the two research teams, the answer may well lie in the so-called global warming “pause” — the misleading idea that global warming has slowed down or stopped over the the past 15 years or so. This claim was used by climate skeptics, to great effect, in their quest to undermine the release of the U.N. Intergovernmental Panel on Climate Change’s Fifth Assessment Report in September 2013 — precisely during the time period that is in question in the latest study.”
“Nonetheless, widely publicized “pause” claims may well have shaped public opinion. “Beginning in September, and lasting several months, coincident with the release of the IPCC report, there was considerable media attention to the concept of the ‘global warming pause,’” observes Maibach. “It is possible that this simple — albeit erroneous — idea helped to convince many people who were previously undecided to conclude that the climate really isn’t changing.”
“Even more likely, however,” Maibach adds, “is that media coverage of the ‘pause’ reinforced the beliefs of people who had previously concluded that global warming is not happening, making them more certain of their beliefs.”
“Journalists take heed: Your coverage has consequences. All those media outlets who trumpeted the global warming “pause” may now be partly responsible for a documented decrease in Americans’ scientific understanding.”
In summary, I am not concerned with the media’s interpretation, or more commonly misinterpretation, of the Polar Vortex, as it plays into our hands by showing more people how little we really know about Earth’s climate system. This image sums up my perspective on the media’s embrace of the Polar Vortex:
[caption id="attachment_54067" align="alignnone" width="568"] memegenerator.net – Click the pic to view at source[/caption]

ren says: January 18, 2014 at 11:45 pm
http://geo.phys.spbu.ru/materials_of_a_conference_2012/STP2012/Veretenenko_%20et_all_Geocosmos2012proceedings.pdf
Interesting, i.e. THE POLAR VORTEX EVOLUTION AS A POSSIBLE REASON FOR THE TEMPORAL VARIABILITY OF SOLAR ACTIVITY EFFECTS ON THE LOWER ATMOSPHERE CIRCULATION S.V. Veretenenko:
“It was revealed that the detected earlier ~60-year oscillations of the amplitude and sign of SA/GCR effects on the troposphere pressure at high and middle latitudes are closely related to the state of a cyclonic vortex forming in the polar stratosphere. A roughly 60- year periodicity was found in the vortex strength affecting the evolution of the large-scale atmospheric circulation and the character of SA/GCR effects. It was shown that the sign reversalsof the correlations between tropospheric pressure and SA/GCR variations coincide well with the transitions between the different states of the vortex. Most pronounced SA/GCR influence on the development of extratropical baric systems is observed when the vortex is strong. The resultsobtained suggest that the evolution of the stratospheric polar vortex plays an important part in the mechanism of solar-atmospheric links.”
“We can see that the temperature in the vortex center decreases with the increase of height and reaches its minimum at the levels 30-50 hPa (20-25 km). The temperature gradients at the vortex edges increase with height in the stratosphere starting from the level 150 hPa, their maximum being observed at the levels 50-10 hPa (20-30 km). In the troposphere temperature gradients are maximal near surface corresponding to Arctic fronts separating the Arctic air from warmer air of middle latitudes. Thus, the vortex is most pronounced at the 50-30 hPa levels where the minimum of stratospheric temperatures and the maximum of temperature gradients at its edges are observed. We can see that the highest values of ion production rate due to GCR are observed in the lower part of the vortex (10-15 km) where temperature gradients start increasing. On the other hand, the 11-year modulation of GCR fluxes is strongest at the heights 20-25 km [Bazilevskaya et al., 2008] where the vortex is most pronounced. Hence, the vortex location seems to be favorable for the mechanisms of solar activity influence on the atmosphere circulation involving GCR variations. It is also favorable for the mechanisms involving solar UV variations, as at these heights (15-25 km) in the polar stratosphere the maximum ozone content is observed. The evolution of the vortex is known to be determined by dynamic coupling between the troposphere and stratosphere via planetary wave propagation, as well as by radiation processes in the stratosphere. So, we can suggest that the mechanism of SA/GCR influence on the troposphere circulation involves changes of the vortex strength associated with changes of the heat-radiation balance in the stratosphere. These changes may be caused by variations of atmosphere transparency in visible and infrared range associated with the effects of ionization and atmospheric electricity variations on cloudy and aerosol particle characteristics [Tinsley, 2008]. Indeed, a considerable increase of aerosol concentration at high latitudes which was most pronounced at the heights 10-12 km and accompanied by the temperature decrease in overlying stratospheric layers was detected during a series of powerful solar proton events on January 15-20, 2005 [Veretenenko et al., 2008]. In turn, the increase of the vortex strength intensifies temperature gradients at its edges (see Fig.4). At the stages of a strong vortex this increase of temperature gradients may be transferred to the troposphere via planetary waves and contribute to the increase of temperature contrasts in tropospheric frontal zones and the intensification of extratropical cyclogenesis.”
5. Conclusions
The results of this study showed that the evolution of the stratospheric polar vortex plays an important part in the mechanism of solar-climatic links. The vortex strength reveals a roughly 60-year periodicity influencing the large-scale atmospheric circulation and the sign of SA/GCR effects on the development of baric systems at middle and high latitudes. The vortex location is favorable for the mechanisms of solar activity influence on the troposphere circulation involving variations of different agents (GCR intensity, UV fluxes). In the periods of a strong vortex changes of the vortex intensity associated with solar activity phenomena seem to affect temperature contrasts in tropospheric frontal zones and the development of extratropical cyclogenesis.”
ren says: January 19, 2014 at 11:39 pm
Solar activity decreases. Grows cosmic rays. Winter will be long ..
http://cosmicrays.oulu.fi/webform/monitor.gif
Added to the WUWT Solar Reference Page and the WUWT Atmosphere Page:
Cosmic Rays
Oulu Neutron Monitor
[caption id="" align="alignnone" width="620"] University of Oulu – Sodankyla Geophysical Observatory – Click the pic to view at source[/caption]
However, not yet added to the WUWT Polar Vortex Reference Pages, as I am not yet convinced that there’s a relationship.
ren says: January 20, 2014 at 6:13 am
AO clearly declining.
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.obs.gif
Added to the WUWT Atmospheric Oscillation page, there’s a version under the Normalized Geopotential Height (GPH) Anomaly image, but the one you provided has better resolution, i.e.:
Arctic Oscillation (AO) Index – 4 Months Prior
[caption id="" align="alignnone" width="578"] NOAA – National Weather Service – Climate Prediction Center – Click the pic to view at source[/caption]
Thank you for your input and contribution. Additional potential content for the WUWT Reference pages, or in support of the relationship between Cosmic Ray and Polar Vorticity, is most welcome.

“Winter turned fierce in the opening weeks of 2009. A bitter cold snap set in over much of the United States, and temperatures plummeted beyond -30 degrees Celsius (-22 F) in parts of the Upper Midwest. On February 2, portions of Western Europe were doused with heavy snow. England received the brunt of the storm with up to 20 centimeters (8 inches) of snow falling in London. It was the heaviest snowfall southeastern England had seen in nearly 20 years, reported BBC News. So why all the nasty weather? Part of the answer lies in the stratosphere, some 20 kilometers (12 miles) above the Earth’s surface.
Starting in January and extending into early February 2009, wind and temperature patterns in the stratosphere changed dramatically. In just a few weeks, temperatures climbed by about 50 degrees Celsius (90 degrees F) on average, with larger spikes in places, and winds flipped direction, changing by nearly 100 meters per second (200 miles per hour). That change influenced weather patterns lower in the atmosphere. These images and the associated animation show how the stratosphere changed and help illustrate why the United States and Europe were in the grip of such odd weather. The globes show temperatures (top) and vorticity (bottom) on January 10 (left) and February 2 (right). (The animation runs from January 10-February 4.) The images are based on assimilated weather observations of the atmosphere from the Goddard Modeling and Assimilation Office at NASA Goddard Space Flight Center.
In the winter, little to no sunlight reaches Earth’s northern extremes. Deprived of energy, the stratosphere over the Arctic grows cold. These were the conditions present on January 10, 2009, as shown in the top left image. The cold air mass creates a low-pressure system in the stratosphere that sits over the Arctic throughout the winter. Farther south, where the Sun is shining, the air is warmer and air pressure is higher in the stratosphere. Air flows away from the high-pressure system towards the low-pressure system. Because the Earth is turning, the air is deflected to the right as it moves north, creating a strong counterclockwise (west to east) current of wind, which scientists call the polar night jet.
The lower pair of images represent the air mass, or polar vortex, that controls the wind pattern. Essentially, the winds are strongest at the edge of the polar vortex (where the pressure difference between the air masses is greatest). The area of red in the lower left image represents polar air that typically sits over the Arctic during January. In general, strong winds circle the red regions, or areas of high vorticity, in a counterclockwise direction. These winds, moving at speeds well above 100 miles per hour, influence winds and weather patterns closer to Earth’s surface. Their influence means that weather in England and Western Europe typically comes from the west. Over England, western winds blow in ocean air warmed by the Atlantic Gulf Stream.
The big change in the Arctic came when the polar vortex ripped apart. A developing weather system in the lower atmosphere traveled upward into the stratosphere. The disturbance nudged into the center of the Arctic air mass, elongating it and eventually splitting it like a cell in mitosis. By February 2, two air masses existed, each with a jet of wind circling it counterclockwise as depicted in the lower right image.
Warm air filled the gap between the two colder air masses, and temperatures high over the North Pole climbed, as shown in the upper right. Now the colder air had shifted farther south over Canada and Siberia. Over North America, this piece of the stratospheric polar vortex had a deep reach into the lower atmosphere (troposphere), which created strong winds from the north that carried cold Arctic air far south into the United States.
In Europe, the split in the air mass actually changed the direction of winds in the lower atmosphere. The second piece of the polar vortex was centered east of Western Europe, as shown in the lower left image, and it too was surrounded by a jet of strong wind moving counterclockwise. Like the segment of the polar vortex over North America, this piece of the polar vortex also had a deep reach into the lower atmosphere. It caused cold continental air to blow in from the east, replacing the warmer air that typically blows in from the west. As the frigid air moved over the North Sea, it picked up moisture, which fell over the United Kingdom and parts of France as heavy snow.”
http://earthobservatory.nasa.gov/IOTD/view.php?id=36972
Stratospheric Temperature
[caption id="" align="alignnone" width="600"] NASA – Click the pic to view at source[/caption]

Stratospheric Vorticity
[caption id="" align="alignnone" width="600"] NASA – Click the pic to view at source[/caption]

Animation of Stratospheric Vorticity:
http://eoimages.gsfc.nasa.gov/images/imagerecords/36000/36972/npole_gmao_200901-02.mov