By WUWT Regular “Just The Facts”
We are pleased to introduce WUWT’s newest addition, the WUWT Northern Polar Vortex Reference Page. We would like to dedicate this page to NBC News and John Holdren, who both seem to need all the help they can get in understanding Polar Vorticity.
“The stratospheric polar vortex is a large-scale region of air that is contained by a strong west-to-east jet stream that circles the polar region. This jet stream is usually referred to as the polar night jet. 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
“Polar vortices are ubiquitous atmospheric structures. In the Solar System, Earth, Mars, Venus, (Jupiter ), Saturn and its moon Titan are known to have well developed vortices in their polar regions at high altitude. These swirling structures are not always present in the atmosphere of a planetary body at all seasons, but they generally form in the winter hemisphere, when the latitudinal equator-to-pole temperature gradients are the strongest. For Earth, Mars, Saturn and Titan, therefore, the axial tilt determines the presence and seasonal variability of their polar vortices. This can be observed, for instance, by looking at the seasonality of the maximum speed of the circumpolar jets (see  for examples related to the Earth and Mars). Venus has a negligible axial tilt; therefore one would expect that the seasonality of its polar vortices is absent. Nonetheless, their seasonality seems to be induced by a dynamical phenomenon, linked to the presence of a quasi-bidiurnal oscillation at mid-latitudes, and extending to high latitudes, rather than by the obliquity of its rotation axis. This oscillation is observed in numerical simulations with global climate models, although its signature depends on the model as well as on model initialisation. A quasi-bidiurnal signal seems also to be present in some analysis of spacecraft data from Venus Express (see for instance ), although it has still to be understood whether its nature and origin are common to the oscillation observed in numerical simulations.” European Planetary Science Congress (Links and Jupiter added within)
Polar Vortices are “caused when an area of low pressure sits at the rotation pole of a planet. This causes air to spiral down from higher in the atmosphere, like water going down a drain.” Universe Today
“Long-term vortices are a frequent phenomenon in the atmospheres of fast rotating planets, like Jupiter and Saturn, for example. Venus rotates slowly, yet it has permanent vortices in its atmosphere at both poles. What is more, the rotation speed of the atmosphere is much greater than that of the planet. “We’ve known for a long time that the atmosphere of Venus rotates 60 times faster than the planet itself, but we didn’t know why. The difference is huge; that is why it’s called super-rotation. And we’ve no idea how it started or how it keeps going.
“The permanence of the Venus vortices contrasts with the case of the Earth. “On the Earth there are seasonal effects and temperature differences between the continental zones and the oceans that create suitable conditions for the formation and dispersal of polar vortices. On Venus there are no oceans or seasons, and so the polar atmosphere behaves very differently,” says Garate-Lopez.” Phys.org
“The stratospheric polar vortex shows quite a bit of day-to-day variability. This variability is caused by weather systems or large-scale waves that move upward from the troposphere into the stratosphere. In the left image (9 January 2010), we see some undulations along the edge of the polar vortex, but the vortex is generally centered on the North Pole. Two weeks later (center image on 23 January 2010) we see the center of the polar vortex pushed away from the North Pole. On a constant latitude circle, PV values are high in the eastern hemisphere and low in the western hemisphere. This is referred to as a wave-1 pattern (a wave-2 pattern can be seen in the vortex breakup section below). The wave-1 pattern develops in the troposphere and moves upward (propagates) into the stratosphere.
These stratospheric waves are forced by the large-scale mountain systems and the land-sea contrasts between the continents and oceans. During the northern winter, these waves are continuously forming and moving upward into the stratosphere. The waves can “break”, much like the waves on a beach. These wave-breaking events erode the vortex and keep the polar region warmer and ozone amounts higher. Often, parts of the polar vortex are pulled away from the main vortex. The image on the right (28 January 2010) shows this, where a large piece of the polar vortex was pulled away from the main vortex (green colored material at the bottom of the image). A comparison between the middle and right images also shows a slight contraction of the polar vortex because of these waves.”
“The polar vortex is a winter phenomena. It develops as the sun sets over the polar region and temperatures cool. During the spring, the sun rises and the absorption of solar radiation by ozone begins to heat the polar stratosphere. This heating eventually causes the vortex to disappear along with the polar night jet. However, this process is helped along by planetary-scale waves that propagate up from the troposphere. This wave event that drives the vortex breakup (or final warming) acts to also increase the temperature of the polar region and ozone levels. We mark the day of the vortex breakup when the winds around the vortex edge decrease below a particular value (about 15 m s -1on the 460 K potential temperature surface).”NASA
WUWT Northern Polar Vortex Reference Page offers focused view on the Northern Polar Vortex, whereas the WUWT Polar Vortex Reference Page offers a more broad overview of Global, Northern and Southern Polar Vorticity. When time permits, there will also be a WUWT Southern Polar Vortex Reference Page forthcoming. The following are some observation on recent Northern Polar Vortex activity from the WUWT Polar Vortex Reference Page:
Northern Hemisphere Temperature Analysis at 10 hPa/mb – Approximately 31,000 meters (101,700 feet) shows a high level split within the Stratospheric Polar Vortex on January 11th, 2014:
The split is also visible in Ozone Mixing Ratios at 30 hPa/mb – Approximately 23,700 meters (77,800 feet);
50 hPa/mb Height Analysis at Approximately 20,100 meters (66,000 feet):
70 hPa/mb Height Analysis – Approximately 18,000 meters (59,000 feet);
and 100 hPa/mb Height Analysis – Approximately 15,000 meters (49,000 feet):
Northern Hemisphere Area Where Temperature is Below 195K or -78C shows significant warming in the last few days;
The Vertical Cross Section of Geopotential Height Anomalies shows that the Polar Vortex has weakened significantly and the Arctic Oscillation swung to negative:
“The Arctic Oscillation refers to an opposing pattern of pressure between the Arctic and the northern middle latitudes. Overall, if the atmospheric pressure is high in the Arctic, it tends to be low in the northern middle latitudes, such as northern Europe and North America. If atmospheric pressure is low in the middle latitudes it is often high in the Arctic. When pressure is high in the Arctic and low in mid-latitudes, the Arctic Oscillation is in its negative phase. In the positive phase, the pattern is reversed.
Meteorologists and climatologists who study the Arctic pay attention to the Arctic Oscillation, because its phase has an important effect on weather in northern locations. The positive phase of the Arctic Oscillation brings ocean storms farther north, making the weather wetter in Alaska, Scotland, and Scandinavia and drier in the western United States and the Mediterranean. The positive phase also keeps weather warmer than normal in the eastern United States, but makes Greenland colder than normal.
In the negative phase of the Arctic Oscillation the patterns are reversed. A strongly negative phase of the Arctic Oscillation brings warm weather to high latitudes, and cold, stormy weather to the more temperate regions where people live.” NSIDC
In terms of why the Polar Vortex weakened and split, and the Atlantic Oscillation swung negative, there are likely several factors. the first being Planetary Waves, i.e. “The polar stratosphere and mesosphere are dynamically altered throughout the winter months by planetary wave activity and its interaction with the mean flow. An extreme interaction leads to polar vortex breakdown and a complete alteration in temperature from the lower stratosphere through the upper atmosphere. However, there are more regular disturbances where the dynamical interactions can alter the upper stratosphere and mesosphere without modification to the lower stratosphere; here these disturbances will be designated as Upper Stratospheric Lower Mesospheric (USLM) disturbances.” American Geophysical Union, Greer et al.
“The polar winter middle atmosphere is a dynamically active region that is driven primarily by wave activity. Planetary waves intermittently disturbed the region at different levels and the most spectacular type of disturbance is a major Sudden Stratospheric Warming (SSW). However, other types of extreme disturbances occur on a more frequent, intraseasonal basis. One such disturbances are synoptic-scale “weather events” observed in lidar and rocket soundings, soundings from the TIMED/SABER instrument and UK Meteorological Office (MetO) assimilated data. These disturbances are most easily identified near 42 km where temperatures are elevated over baseline conditions by a remarkable 50 K and an associated cooling is observed near 75 km. As these disturbances have a coupled vertical structure extending into the lower mesosphere, they are termed Upper Stratospheric/Lower Mesospheric (USLM) disturbances.”American Meteorological Society Conference, Greer et al. 2013
Recent Planetary Wave activity can be see on this Zonal Wave #1 Amplitude Jan, Feb, March Time Series;
Zonal Wave #2 Amplitude Jan, Feb, March Time Series;
and Zonal Wave #3 Amplitude Jan, Feb, March Time Series:
Another likely factor that weakened and split the Polar Vortex is Eddy Heat, i.e. “strong negative fluxes indicate poleward flux of heat via eddies. Multiple strong poleward episodes will result in a smaller polar vortex, Sudden Stratospheric Warmings and an earlier transition from winter to summer circulations. Relatively small flux amplitudes will result in a more stable polar vortex and will extend the winter circulation well into the Spring” NOAA
Here you can see that 10 day Averaged Eddy Heat Flux Towards The North Pole At 100mb neared a record daily maximum in early January:
A third potential factor in Polar Vortex behavior that has been proposed is that “geomagnetic activity (used as a measure of solar wind parameters)” plays a role in the “variability of large-scale climate patterns and on changes in the global temperature. We have found positive statistically significant correlations between global temperature and the distribution of surface temperature over Eurasia, the East and Equatorial Pacific and over the North Atlantic for the period 1966-2009 correspond to large-scale climate patterns defined by climate indices. We found very similar positive correlations between geomagnetic activity and the distribution of surface temperature in the mentioned regions. As an effect of geomagnetic storms, energetic particles penetrate from the magnetosphere into the region of the stratospheric polar vortex. The increase of temperature and pressure can be observed over northern Canada. The vortex shifts towards Europe, rotates counter-clockwise and the wind blows from the polar region over Greenland southwards. It diverts the warm flow proceeding northward over the Atlantic, eastward along the deep Icelandic low extending as far as the Barents Sea and takes part in warming Eurasia. The strengthened zonal flow from Siberia cools the western Pacific with the impact on the warming of the equatorial and eastern Pacific when also a distinct 1976-78 climate shift occurred. Processes in the Atlantic and Pacific play a significant role and a time delay (wind forcing over the previous 1-4 yr) appears to be the most important for the relocation of the oceanic gyres. Results showing statistically significant relations between time series for geomagnetic activity, for the sum of climate indices and for the global temperature help to verify findings concerning the chain of processes from the magnetosphere to the troposphere.” Studia Geophysica & Geodaetica, Bucha 2012
and the Magnetosphere was rocking and rolling:
However, there is limited evidence to support the influence of Solar activity on Polar Vorticity and in the past Leif has been dismissive of the potential that Solar influences on the upper atmosphere could influence Earth’s climate, i.e.:
Leif Svalgaard says: March 6, 2011 at 12:13 pm
Just The Facts says: March 6, 2011 at 11:03 am
indicate that the causative mechanism behind proton aurora precipitation during high dynamic pressure is connected to the compression of the magnetosphere, which is directly related to the solar wind dynamic pressure. [and other quotes]
“You keep bringing up influences on the upper atmosphere [which are not disputed - but makes for good fill-material that looks like science], but all of these things are either not related to climate at all or, at best, only marginally and unconvincing.
Again, your bar is much too low [to be generous].”
Regardless of the causes, it appears that the result is that an Upper Stratospheric/Lower Mesospheric (USLM) disturbance occurred, i.e. “USLM Disturbance criteria are established, based on stratopause warmings at the 2 hPa level, to create climatologies in both hemispheres that delineate their timing, frequency, and geographic location. USLM disturbances occur on average 2.3 times per winter in the Northern Hemisphere (NH)(November through March) and 1.6 times per winter in the Southern Hemisphere (SH)(May through September), persist on average for 8 days in the NH and only 4 days in the SH, occur most frequently in December (July) in the Northern (Southern) Hemisphere, and are predominantly located in the longitude sector between 0oE and 90oE in both hemispheres. This is the ﬁrst work to show that all major Sudden Stratospheric Warmings (SSWs) over the 20.5 year data record are preceded by USLM disturbances. One third of USLM disturbances evolve into a major SSW; only 22% of minor SSWs evolve into a major SSW. USLM disturbances and minor SSWs illustrate, at times, similar occurrence statistics, but the minor warming criteria seem to include a more diverse range of dynamical conditions. USLM disturbances are more specific in their dynamical construct with strong baroclinicity being a necessary condition. Potential vorticity analysis indicates that all USLM events occur with planetary wave breaking and that subsequent baroclinic instability may lead to the development of USLM disturbances. A climatology of polar winter stratopause warmings and associated planetary wave breaking”. Greer et al. 2013
“The typical thermal structure of USLM disturbances is dipolar in nature at 2.0 hPa with strong thermal gradients across the polar vortex. From the assimilated data, we find that the geographic preference of the anomalously warm temperatures at 2.0 hPa are located on the East side of the polar low, while there is a related cool pool of air located on the West side. These geographic preferences and observed amplification in temperature help to support the proposed dynamical process of baroclinic instability. Indirect circulations are induced, and to preserve continuity, cells of ageostrophic and vertical motions occur well into the mesosphere, and potentially into the thermosphere. We find that the average frequency of USLM events is 1.63 events per season in the Northern Hemisphere. In addition, the assimilated data indicates that all Sudden Stratospheric Warmings (SSWs) are preceded by USLM events; SSW events occur with a frequency of 0.84 events per season (Northern Hemisphere). USLM disturbances persist from three to ten days and tend to precede SSW events by several days, although there may be multiple USLM disturbances prior to an SSW event occurring. Lastly we exhibit how USLM disturbances differ between the Northern and Southern poles, including differences in frequency and intensity. An open question is whether these frequent USLM polar winter disturbances impact the thermosphere and ionosphere. American Geophysical Union, Greer et al.
“Analysis of planetary wave breaking and EP-flux of individual and composite USLM events indicate an increase in breaking near the 0.1 hPa level, approximately 10 km above the extreme thermal anomaly at the stratopause in the days leading up to the peak of the event. Vertical coupling of the atmosphere during this event is illustrated in the progression of these events and their impact on the thermal structure, zonal mean wind, polar vortex and conditions that have the potential to support a secondary baroclinic instability (including the Charney-Stern criteria for instability the role of baroclinic/barotropic instabilities). In addition, USLM disturbances appear to have front-like behavior analogous to the troposphere. Broader impacts of these disturbances and the dynamics associated with them influence gravity wave generation/propagation, vertical air motion, chemical tracer transport, precondition of the atmosphere for SSWs and the potential to couple with the thermosphere through tides. American Meteorological Society Conference, Greer et al. 2013
The Upper Stratosphere Lower Mesosphere (USLM) Disturbance can be seen on this Jan, Feb, March Zonal Temperature Anomaly Time Series;
and the impact of the USLM can be seen in the rapid increase in 10-hPa/mb Height Temperature Anomalies – Atmospheric Temperature Anomalies At Approximately 31,000 meters (101,700 feet) over East Asia:
You can see more on current Northern Polar Vortex conditions on the new WUWT Northern Polar Vortex Reference Page. I addition, if you have not had the opportunity to review WUWT’s other Reference Pages it is highly recommended:
- Atmosphere Page
- Atmospheric Oscillation Page
- ENSO (El Nino/La Nina Southern Oscillation) Page
- “Extreme Weather” Page
- Geomagnetism Page
- Global Climate Page
- Global Temperature Page
- Ocean Page
- Oceanic Oscillation Page
- Polar Vortex Page
- Paleoclimate Page
- Potential Climatic Variables Page
- WUWT Northern Polar Vortex Reference Page.
- Northern Regional Sea Ice Page
- Sea Ice Page
- Solar Page
- Spencer and Braswell Papers
- Tornado Page
- Tropical Cyclone Page
- US Climatic History Page
- US Weather Page
Please note that WUWT cannot vouch for the accuracy of the data within the Reference Pages, as WUWT is simply an aggregator. All of the data is linked from third party sources. If you have doubts about the accuracy of any of the graphs on the WUWT Reference Pages, or have any suggested additions or improvements to any of the pages, please let us know in comments below.