A circumpolar vortex, or simply polar vortex, is a large region of cold, rotating air that encircles both of Earth's polar regions. Polar vortices also exist on other rotating, low-obliquity planetary bodies. The term polar vortex can be used to describe two distinct phenomena; the stratospheric polar vortex, and the tropospheric polar vortex. The stratospheric and tropospheric polar vortices both rotate in the direction of the Earth's spin, but they are distinct phenomena that have different sizes, structures, seasonal cycles, and impacts on weather.
The stratospheric polar vortex is an area of high-speed, cyclonically rotating winds around 15 km to 50 km high, poleward of 50°, and is strongest in winter. It forms in Autumn when Arctic or Antarctic temperatures cool rapidly as the polar night begins. The increased temperature difference between the pole and the tropics causes strong winds and the Coriolis effect causes the vortex to spin up. The stratospheric polar vortex breaks down in Spring as the polar night ends. A sudden stratospheric warming (SSW) is an event that occurs when the stratospheric vortex breaks down during winter, and can have significant impacts on surface weather.
The tropospheric polar vortex is often defined as the area poleward of the tropospheric jet stream. The equatorward edge is around 40° to 50°, and it extends from the surface up to around 10 km to 15 km. Its yearly cycle differs from the stratospheric vortex because the tropospheric vortex exists all year, but is similar to the stratospheric vortex since it is also strongest in winter when the polar regions are coldest.
The tropospheric polar vortex was first described as early as 1853. The stratospheric vortex's SSWs were discovered in 1952 with radiosonde observations at altitudes higher than 20 km. The tropospheric polar vortex was mentioned frequently in the news and weather media in the cold North American winter of 2013–2014, popularizing the term as an explanation of very cold temperatures.[self-published source?] The tropospheric vortex increased in public visibility in 2021 as a result of extreme frigid temperatures in the central United States, with experts linking its effects to climate change.
Ozone depletion occurs within the polar vortices – particularly over the Southern Hemisphere – reaching a maximum depletion in the spring.
Arctic and Antarctic vortices
When the tropospheric vortex of the Arctic was strong, it had a well defined and nearly circular in shape, there was a single vortex with a jet stream that is well constrained near the polar front, and the Arctic air is well contained. When the northern tropospheric vortex weakened, it will break into two or more smaller vortices, the strongest of which are near Baffin Island, Nunavut, and the other over northeast Siberia. When it is very weak, the flow of Arctic air becomes more disorganized, and masses of cold Arctic air can push equatorward, bringing with them a rapid and sharp temperature drop.
A deep freeze that gripped much of the United States and Canada in late January 2019 has been blamed on a "polar vortex". This is not the scientifically correct use of the term polar vortex, but instead is referring to outbreaks of cold Arctic air caused by a weakened polar vortex. The US National Weather Service warned that frostbite is possible within just 10 minutes of being outside in such extreme temperatures, and hundreds of schools, colleges and universities in the affected areas were closed. Around 21 people died in US due to severe frostbite. States within the midwest region of the United States had windchills just above -50 °F (-45 °C). The Polar vortex is also thought to have had effects in Europe. For example, the 2013–14 United Kingdom winter floods were blamed on the Polar vortex bringing severe cold in the United States and Canada. Similarly, the severe cold in the United Kingdom in the winters of 2009/10 and 2010/11 were also blamed on the Polar vortex.
The Antarctic vortex of the Southern Hemisphere is a single low-pressure zone that is found near the edge of the Ross ice shelf, near 160 west longitude. When the polar vortex is strong, the mid-latitude Westerlies (winds at the surface level between 30° and 60° latitude from the west) increase in strength and are persistent. When the polar vortex is weak, high-pressure zones of the mid-latitudes may push poleward, moving the polar vortex, jet stream, and polar front equatorward. The jet stream is seen to "buckle" and deviate south. This rapidly brings cold dry air into contact with the warm, moist air of the mid-latitudes, resulting in a rapid and dramatic change of weather known as a "cold snap".
In Australia, the polar vortex, known there as a "polar blast" or "polar plunge", is a cold front that drags air from Antarctica which brings rain showers, snow (typically inland, with blizzards occurring in the highlands), gusty icy winds, and hail in the south-eastern parts of the country, such as in Victoria, Tasmania, the southeast coast of South Australia and the southern half of New South Wales (but only on the windward side of the Great Dividing Range, whereas the leeward side will be affected by foehn winds).
The bases of the two polar vortices are located in the middle and upper troposphere and extend into the stratosphere. Beneath that lies a large mass of cold, dense Arctic air. The interface between the cold dry air mass of the pole and the warm moist air mass farther south defines the location of the polar front. The polar front is centered, roughly at 60° latitude. A polar vortex strengthens in the winter and weakens in the summer because of its dependence on the temperature difference between the equator and the poles.[self-published source?]
Polar cyclones are low-pressure zones embedded within the polar air masses, and exist year-round. The stratospheric polar vortex develops at latitudes above the subtropical jet stream. Horizontally, most polar vortices have a radius of less than 1,000 kilometres (620 mi). Since polar vortices exist from the stratosphere downward into the mid-troposphere, a variety of heights/pressure levels are used to mark its position. The 50 hPa pressure surface is most often used to identify its stratospheric location. At the level of the tropopause, the extent of closed contours of potential temperature can be used to determine its strength. Others have used levels down to the 500 hPa pressure level (about 5,460 metres (17,910 ft) above sea level during the winter) to identify the polar vortex.
Duration and strength
Polar vortices are weakest during summer and strongest during winter. Extratropical cyclones that migrate into higher latitudes when the polar vortex is weak can disrupt the single vortex creating smaller vortices (cold-core lows) within the polar air mass. Those individual vortices can persist for more than a month.
Volcanic eruptions in the tropics can lead to a stronger polar vortex during winter for as long as two years afterwards. The strength and position of the polar vortex shapes the flow pattern in a broad area about it. An index which is used in the northern hemisphere to gauge its magnitude is the Arctic oscillation.
When the Arctic vortex is at its strongest, there is a single vortex, but normally, the Arctic vortex is elongated in shape, with two cyclone centers, one over Baffin Island in Canada and the other over northeast Siberia. When the Arctic pattern is at its weakest, subtropic air masses can intrude poleward causing the Arctic air masses to move equatorward, as during the Winter 1985 Arctic outbreak. The Antarctic polar vortex is more pronounced and persistent than the Arctic one. In the Arctic the distribution of land masses at high latitudes in the Northern Hemisphere gives rise to Rossby waves which contribute to the breakdown of the polar vortex, whereas in the Southern Hemisphere the vortex is less disturbed. The breakdown of the polar vortex is an extreme event known as a sudden stratospheric warming, here the vortex completely breaks down and an associated warming of 30–50 °C (54–90 °F)[clarification needed] over a few days can occur.
The waxing and waning of the polar vortex is driven by the movement of mass and the transfer of heat in the polar region. In the autumn, the circumpolar winds increase in speed and the polar vortex rises into the stratosphere. The result is that the polar air forms a coherent rotating air mass: the polar vortex. As winter approaches, the vortex core cools, the winds decrease, and the vortex energy declines. Once late winter and early spring approach the vortex is at its weakest. As a result, during late winter, large fragments of the vortex air can be diverted into lower latitudes by stronger weather systems intruding from those latitudes. In the lowest level of the stratosphere, strong potential vorticity gradients remain, and the majority of that air remains confined within the polar air mass into December in the Southern Hemisphere and April in the Northern Hemisphere, well after the breakup of the vortex in the mid-stratosphere.
The breakup of the northern polar vortex occurs between mid March to mid May. This event signifies the transition from winter to spring, and has impacts on the hydrological cycle, growing seasons of vegetation, and overall ecosystem productivity. The timing of the transition also influences changes in sea ice, ozone, air temperature, and cloudiness. Early and late polar breakup episodes have occurred, due to variations in the stratospheric flow structure and upward spreading of planetary waves from the troposphere.[clarification needed] As a result of increased waves into the vortex, the vortex experiences more rapid warming than normal, resulting in an earlier breakup and spring. When the breakup comes early, it is characterized by[clarification needed] with persistent of remnants of the vortex. When the breakup is late, the remnants dissipate rapidly. When the breakup is early, there is one warming period from late February to middle March. When the breakup is late, there are two warming periods, one January, and one in March. Zonal mean temperature, wind, and geopotential height exert varying deviations from their normal values before and after early breakups, while the deviations remain constant before and after late breakups. Scientists are connecting a delay in the Arctic vortex breakup with a reduction of planetary wave activities, few stratospheric sudden warming events, and depletion of ozone.[clarification needed]
Sudden stratospheric warming events are associated with weaker polar vortices. This warming of stratospheric air can reverse the circulation in the Arctic Polar Vortex from counter-clockwise to clockwise. These changes aloft force changes in the troposphere below. An example of an effect on the troposphere is the change in speed of the Atlantic Ocean circulation pattern. A soft spot just south of Greenland is where the initial step of downwelling occurs, nicknamed the "Achilles Heel of the North Atlantic". Small amounts of heating or cooling traveling from the polar vortex can trigger or delay downwelling, altering the Gulf Stream Current of the Atlantic, and the speed of other ocean currents. Since all other oceans depend on the Atlantic Ocean's movement of heat energy, climates across the planet can be dramatically affected. The weakening or strengthening of the polar vortex can alter the sea circulation more than a mile beneath the waves. Strengthening storm systems within the troposphere that cool the poles, intensify the polar vortex. La Niña–related climate anomalies significantly strengthen the polar vortex. Intensification of the polar vortex produces changes in relative humidity as downward intrusions of dry, stratospheric air enter the vortex core. With a strengthening of the vortex comes a longwave cooling due to a decrease in water vapor concentration near the vortex. The decreased water content is a result of a lower tropopause within the vortex, which places dry stratospheric air above moist tropospheric air. Instability is caused when the vortex tube, the line of concentrated vorticity, is displaced. When this occurs, the vortex rings become more unstable and prone to shifting by planetary waves. The planetary wave activity in both hemispheres varies year-to-year, producing a corresponding response in the strength and temperature of the polar vortex. The number of waves around the perimeter of the vortex are related to the core size; as the vortex core decreases, the number of waves increase.
The degree of the mixing of polar and mid-latitude air depends on the evolution and position of the polar night jet. In general, the mixing is less inside the vortex than outside. Mixing occurs with unstable planetary waves that are characteristic of the middle and upper stratosphere in winter. Prior to vortex breakdown, there is little transport of air out of the Arctic Polar Vortex due to strong barriers above 420 km (261 miles). The polar night jet which exists below this, is weak in the early winter. As a result, it does not deviate any descending polar air, which then mixes with air in the mid-latitudes. In the late winter, air parcels do not descend as much, reducing mixing. After the vortex is broken up, the ex-vortex air is dispersed into the middle latitudes within a month.
Sometimes, a mass of the polar vortex breaks off before the end of the final warming period. If large enough, the piece can move into Canada and the Midwestern, Central, Southern, and Northeastern United States. This diversion of the polar vortex can occur due to the displacement of the polar jet stream; for example, the significant northwestward direction of the polar jet stream in the western part of the United States during the winters of 2013–2014, and 2014–2015. This caused warm, dry conditions in the west, and cold, snowy conditions in the north-central and northeast. Occasionally, the high-pressure air mass, called the Greenland Block, can cause the polar vortex to divert to the south, rather than follow its normal path over the North Atlantic.
A study in 2001 found that stratospheric circulation can have anomalous effects on weather regimes. In the same year, researchers found a statistical correlation between weak polar vortex and outbreaks of severe cold in the Northern Hemisphere. In later years, scientists identified interactions with Arctic sea ice decline, reduced snow cover, evapotranspiration patterns, NAO anomalies or weather anomalies which are linked to the polar vortex and jet stream configuration.
Since the early 2000s, climate models have consistently identified that global warming will gradually push jet streams poleward. In 2008, this was confirmed by observational evidence, which proved that from 1979 to 2001, the northern jet stream moved northward at an average rate of 2.01 kilometres (1.25 mi) per year, with a similar trend in the Southern Hemisphere jet stream. Climate scientists have hypothesized that the jet stream will also gradually weaken as a result of global warming. Trends such as Arctic sea ice decline, reduced snow cover, evapotranspiration patterns, and other weather anomalies have caused the Arctic to heat up faster than other parts of the globe, in what is known as the Arctic amplification. In 2021-2022, it was found that since 1979, the warming within the Arctic Circle has been nearly four times faster than the global average, and some hotspots in the Barents Sea area warmed up to seven times faster than the global average. While the Arctic remains one of the coldest places on Earth today, the temperature gradient between it and the warmer parts of the globe will continue to diminish with every decade of global warming as the result of this amplification. If this gradient has a strong influence on the jet stream, then it will eventually become weaker and more variable in its course, which would allow more cold air from the polar vortex to leak mid-latitudes and slow the progression of Rossby Waves, leading to more persistent and more extreme weather.
The hypothesis above is closely associated with Jennifer Francis, who had first proposed it in a 2012 paper co-authored by Stephen J. Vavrus. While some paleoclimate reconstructions have suggested that the polar vortex becomes more variable and causes more unstable weather during periods of warming back in 1997, this was contradicted by climate modelling, with PMIP2 simulations finding in 2010 that the Arctic oscillation was much weaker and more negative during the Last Glacial Maximum, and suggesting that warmer periods have stronger positive phase AO, and thus less frequent leaks of the polar vortex air. However, a 2012 review in the Journal of the Atmospheric Sciences noted that "there [has been] a significant change in the vortex mean state over the twenty-first century, resulting in a weaker, more disturbed vortex.", which contradicted the modelling results but fit the Francis-Vavrus hypothesis. Additionally, a 2013 study noted that the then-current CMIP5 tended to strongly underestimate winter blocking trends, and other 2012 research had suggested a connection between declining Arctic sea ice and heavy snowfall during midlatitude winters.
In 2013, further research from Francis connected reductions in the Arctic sea ice to extreme summer weather in the northern mid-latitudes, while other research from that year identified potential linkages between Arctic sea ice trends and more extreme rainfall in the European summer, At the time, it was also suggested that this connection between Arctic amplification and jet stream patterns was involved in the formation of Hurricane Sandy and played a role in the Early 2014 North American cold wave In 2015, Francis' next study concluded that highly amplified jet-stream patterns are occurring more frequently in the past two decades. Hence, continued heat-trapping emissions favour increased formation of extreme events caused by prolonged weather conditions.
Studies published in 2017 and 2018 identified stalling patterns of Rossby waves in the northern hemisphere jet stream as the culprit behind other almost stationary extreme weather events, such as the 2018 European heatwave, the 2003 European heat wave, 2010 Russian heat wave or the 2010 Pakistan floods, and suggested that these patterns were all connected to Arctic amplification. Further work from Francis and Vavrus that year suggested that amplified Arctic warming is observed as stronger in lower atmospheric areas because the expanding process of warmer air increases pressure levels which decreases poleward geopotential height gradients. As these gradients are the reason that cause west to east winds through the thermal wind relationship, declining speeds are usually found south of the areas with geopotential increases. In 2017, Francis explained her findings to the Scientific American: "A lot more water vapor is being transported northward by big swings in the jet stream. That's important because water vapor is a greenhouse gas just like carbon dioxide and methane. It traps heat in the atmosphere. That vapor also condenses as droplets we know as clouds, which themselves trap more heat. The vapor is a big part of the amplification story—a big reason the Arctic is warming faster than anywhere else."
In a 2017 study conducted by climatologist Dr. Judah Cohen and several of his research associates, Cohen wrote that "[the] shift in polar vortex states can account for most of the recent winter cooling trends over Eurasian midlatitudes". A 2018 paper from Vavrus and others linked Arctic amplification to more persistent hot-dry extremes during the midlatitude summers, as well as the midlatitude winter continental cooling. Another 2017 paper estimated that when the Arctic experiences anomalous warming, primary production in the North America goes down by between 1% and 4% on average, with some states suffering up to 20% losses. A 2021 study found that a stratospheric polar vortex disruption is linked with extreme cold winter weather across parts of Asia and North America, including the February 2021 North American cold wave. Another 2021 study identified a connection between the Arctic sea ice loss and the increased size of wildfires in the Western United States.
However, because the specific observations are considered short-term observations, there is considerable uncertainty in the conclusions. Climatology observations require several decades to definitively distinguish various forms of natural variability from climate trends. This point was stressed by reviews in 2013 and in 2017. A study in 2014 concluded that Arctic amplification significantly decreased cold-season temperature variability over the Northern Hemisphere in recent decades. Cold Arctic air intrudes into the warmer lower latitudes more rapidly today during autumn and winter, a trend projected to continue in the future except during summer, thus calling into question whether winters will bring more cold extremes. A 2019 analysis of a data set collected from 35 182 weather stations worldwide, including 9116 whose records go beyond 50 years, found a sharp decrease in northern midlatitude cold waves since the 1980s.
Moreover, a range of long-term observational data collected during 2010s and published in 2020s now suggests that the intensification of Arctic amplification since the early 2010s was not linked to significant changes on midlatitude atmospheric patterns. State-of-the-art modelling research of PAMIP (Polar Amplification Model Intercomparison Project) improved upon the 2010 findings of PMIP2 - it did find that sea ice decline would weaken the jet stream and increase the probability of atmospheric blocking, but the connection was very minor, and typically insignificant next to interannual variability. In 2022, a follow-up study found that while the PAMIP average had likely underestimated the weakening caused by sea ice decline by 1.2 to 3 times, even the corrected connection still amounts to only 10% of the jet stream's natural variability.Additionally, a 2021 study found that while jet streams had indeed slowly moved polewards since 1960 as was predicted by models, they did not weaken, in spite of a small increase in waviness. A 2022 re-analysis of the aircraft observational data collected over 2002–2020 suggested that the North Atlantic jet stream had actually strengthened. Finally, a 2021 study was able to reconstruct jet stream patterns over the past 1,250 years based on Greenland ice cores, and found that all of the recently observed changes remain within range of natural variability: the earliest likely time of divergence is in 2060, under the Representative Concentration Pathway 8.5 which implies continually accelerating greenhouse gas emissions.
The chemistry of the Antarctic polar vortex has created severe ozone depletion, although the effect has been weakening since the 2000s. It is expected to return to 1980 levels in about 2075.  The nitric acid in polar stratospheric clouds reacts with chlorofluorocarbons to form chlorine, which catalyzes the photochemical destruction of ozone. Chlorine concentrations build up during the polar winter, and the consequent ozone destruction is greatest when the sunlight returns in spring. These clouds can only form at temperatures below about −80 °C (−112 °F).
Since there is greater air exchange between the Arctic and the mid-latitudes, ozone depletion at the north pole is much less severe than at the south. Accordingly, the seasonal reduction of ozone levels over the Arctic is usually characterized as an "ozone dent", whereas the more severe ozone depletion over the Antarctic is considered an "ozone hole". That said, chemical ozone destruction in the 2011 Arctic polar vortex attained, for the first time, a level clearly identifiable as an Arctic "ozone hole".
- Polar amplification
- Saturn's hexagon – a persisting hexagonal cloud pattern around the north pole of Saturn
- Windward Performance Perlan II – will be used to study the northern polar vortex
- Polar front
- Cut-off low
- Read, P.L. (August 2011). "Dynamics and circulation regimes of terrestrial planets". Planetary and Space Science. 59 (10): 900–914. Bibcode:2011P&SS...59..900R. doi:10.1016/j.pss.2010.04.024.
- "Air Maps", Littell's Living Age No. 495, 12 November 1853, p. 430.
- "GEOS-5 Analyses and Forecasts of the Major Stratospheric Sudden Warming of January 2013" (Press release). Goddard Space Flight Center. Retrieved January 8, 2014.
- "Polar Vortex: The Science, Myth & Media Hype Behind North American Weather Phenomenon".
- Plumer, Brad (16 February 2021). "A Glimpse of America's Future: Climate Change Means Trouble for Power Grids". The New York Times.
- "Polar vortex". Glossary of Meteorology. American Meteorological Society. June 2000. Retrieved 15 June 2008.
- "Casualty". BBC News. 1 Feb 2019. Retrieved 12 Feb 2019.
- "Polar vortex: What is it and how does it happen?". BBC video. 30 Jan 2019. Retrieved 31 Jan 2019.
- "UK Flooding and the Science of Climate Change". 9 February 2014.
- "Britain is about to get very, very cold". Independent.co.uk. 7 November 2016.
- "Stratospheric Polar Vortex Influences Winter Cold, Researchers Say" (Press release). American Association for the Advancement of Science. December 3, 2001. Retrieved May 23, 2015.
- "Polar Blast Set To Hit Australia This Weekend, First in 15 Years". Science Times. 21 Aug 2020. Retrieved 25 September 2020.
- "'Twin peaks': Sydney prepares for double burst of polar chill". Sydney Morning Herald. 9 May 2018. Retrieved 25 September 2020.
- Halldór Björnsson. "Global circulation". Archived from the original on March 24, 2010. Retrieved September 2, 2016.. Veðurstofa Íslands. Retrieved on 2008-06-15.
- Hartmann, D; Schoeberl, M (1991). "Mixing of polar vortex air into middle latitudes as revealed by tracer-tracer scatterplots". Journal of Geophysical Research. 102 (D11): 13119. Bibcode:1997JGR...10213119W. doi:10.1029/96JD03715.
- Cavallo, Steven M.; Hakim, Gregory J. (April 2009). "Potential Vorticity Diagnosis of a Tropopause Polar Cyclone". Monthly Weather Review. 137 (4): 1358–1371. Bibcode:2009MWRv..137.1358C. doi:10.1175/2008MWR2670.1. S2CID 16226331.
- Kolstad, Erik W.; Breiteig, Tarjei; Scaife, Adam A. (April 2010). "The association between stratospheric weak polar vortex events and cold air outbreaks in the Northern Hemisphere". Quarterly Journal of the Royal Meteorological Society. 136 (649): 887. arXiv:0906.0027. Bibcode:2010EGUGA..12.5739K. doi:10.1002/qj.620. S2CID 119249497.
- Abdolreza Kashki & Javad Khoshhal (2013-11-22). "Investigation of the Role of Polar Vortex in Iranian First and Last Snowfalls". Journal of Geology and Geography. 5 (4). ISSN 1916-9779. Archived from the original on 2016-03-04. Retrieved 2014-01-30.
- Erik A. Rasmussen and John Turner (2003). Polar lows: mesoscale weather systems in the polar regions. Cambridge University Press. p. 174. ISBN 978-0-521-62430-5.
- Robock, Alan (2000). "Volcanic eruptions and climate" (PDF). Reviews of Geophysics. 38 (2): 191–219. Bibcode:2000RvGeo..38..191R. doi:10.1029/1998RG000054. S2CID 1299888. Archived from the original (PDF) on 2020-02-19.
- Todd Mitchell (2004). Arctic Oscillation (AO) time series, 1899 – June 2002 Archived 2003-12-12 at the Wayback Machine. University of Washington. Retrieved on 2009-03-02.
- Kevin Myatt (2005-01-17). Cold enough for snow, and more's on the way Archived 2013-02-01 at archive.today. Roanoke Times. Retrieved on 2012-02-24.
- Nash, E; Newman, P; Rosenfield, J; Schoeberl, M (2012). "An objective determination of the polar vortex using Ertel's potential vorticity". Journal of Geophysical Research. 101 (D5): 9471–9478. Bibcode:1996JGR...101.9471N. doi:10.1029/96JD00066.
- Li, L; Li, C; Pan, Y (2012). "On the differences and climate impacts of early and late stratospheric polar vortex breakup". Advances in Atmospheric Sciences. 29 (5): 1119–1128. Bibcode:2012AdAtS..29.1119L. doi:10.1007/s00376-012-1012-4. S2CID 123846176.
- Wei, K; Chen, W; Huang, R (2007). "Dynamical diagnosis of the breakup of the stratospheric polar vortex in the northern hemisphere". Science in China Series D: Earth Sciences. 50 (9): 1369–1379. Bibcode:2007ScChD..50.1369W. doi:10.1007/s11430-007-0100-2. S2CID 195309667.
- Reichler, Tom; Kim, J; Manzini, E; Kroger, J (2012). "A stratospheric connection to Atlantic climate variability". Nature Geoscience. 5 (11): 783–787. Bibcode:2012NatGe...5..783R. doi:10.1038/ngeo1586.
- Ripesi, Patrizio; et al. (2012). "The February 2010 Artcic Oscillation Index and its stratospheric connection" (PDF). Quarterly Journal of the Royal Meteorological Society. 138 (669): 1961–1969. Bibcode:2012QJRMS.138.1961R. doi:10.1002/qj.1935. S2CID 122729063.
- Reichler, Tom; Kim, J; Manzini, E; Kroger, J (2012). "A stratospheric connection to Atlantic climate variability". Nature Geoscience. 5 (11): 783–787. Bibcode:2012NatGe...5..783R. doi:10.1038/ngeo1586.
- Limpasuvan, Varavut; Hartmann, Dennis L.; Thompson, David W.J.; Jeev, Kumar; Yung, Yuk L. (2005). "Stratosphere-troposphere evolution during polar vortex intensification" (PDF). Journal of Geophysical Research. 110 (D24): 27. Bibcode:2005JGRD..11024101L. CiteSeerX 10.1.1.526.9159. doi:10.1029/2005JD006302.
- Cavallo, S; Hakim, G.J. (2013). "Physical mechanisms of tropopause polar vortex intensity change". Journal of the Atmospheric Sciences. 70 (11): 3359–3373. Bibcode:2013JAtS...70.3359C. doi:10.1175/JAS-D-13-088.1.
- Hartmann, D; Schoeberl, M (1991). "The dynamics of the stratospheric polar vortex and its relation to springtime ozone depletions" (PDF). Science. 251 (4989): 46–52. Bibcode:1991Sci...251...46S. doi:10.1126/science.251.4989.46. PMID 17778602. S2CID 24664477. Archived from the original (PDF) on 2019-03-02.
- Widnall, S; Sullivan, J (1973). "On the stability of vortex rings". Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences. 332 (1590): 335–353. Bibcode:1973RSPSA.332..335W. doi:10.1098/rspa.1973.0029. S2CID 119959924.
- Manney, G; Zurek, R; O'Neill, A; Swinbank, R (1994). "On the motion of air through the stratospheric polar vortex". Journal of the Atmospheric Sciences. 51 (20): 2973–2994. Bibcode:1994JAtS...51.2973M. doi:10.1175/1520-0469(1994)051<2973:otmoat>2.0.co;2.
- Waugh, D; Plumb, R; Elkins, J; Fahey, D; Boering, K; Dutton, G; Lait, L (2012). "Mixing of polar vortex air into middle latitudes as revealed by tracer-tracer scatterplots". Journal of Geophysical Research: Atmospheres. 102 (D11): 13119–13134. Bibcode:1997JGR...10213119W. doi:10.1029/96JD03715.
- "The Warm West, Cool East U.S. Temperature Divide | Climate Nexus". Archived from the original on 2015-12-07. Retrieved 2015-11-26.
- Erdman, Jon (2014). "What's a Polar Vortex?: The Science Behind Arctic Outbreaks". wunderground. Retrieved 25 February 2014.
- Baldwin, M.P.; Dunkerton, TJ (2001). "Stratospheric Harbingers of Anomalous Weather Regimes". Science. 294 (5542): 581–584. Bibcode:2001Sci...294..581B. doi:10.1126/science.1063315. PMID 11641495. S2CID 34595603.
- NASA (December 21, 2001). "Stratospheric Polar Vortex Influences Winter Cold". Earth Observatory. Archived from the original on March 16, 2010. Retrieved January 7, 2014.
- Song, Yucheng; Robinson, Walter A. (2004). "Dynamical Mechanisms for Stratospheric Influences on the Troposphere". Journal of the Atmospheric Sciences. 61 (14): 1711–1725. Bibcode:2004JAtS...61.1711S. doi:10.1175/1520-0469(2004)061<1711:DMFSIO>2.0.CO;2.
- Archer, Cristina L.; Caldeira, Ken (18 April 2008). "Historical trends in the jet streams". Geophysical Research Letters. 35 (8). doi:10.1029/2008GL033614.
- "Jet stream found to be permanently drifting north". Associated Press. 2008-04-18. Retrieved 7 October 2022.
- Rantanen, Mika; Karpechko, Alexey Yu; Lipponen, Antti; Nordling, Kalle; Hyvärinen, Otto; Ruosteenoja, Kimmo; Vihma, Timo; Laaksonen, Ari (11 August 2022). "The Arctic has warmed nearly four times faster than the globe since 1979". Communications Earth & Environment. 3 (1): 1–10. doi:10.1038/s43247-022-00498-3. ISSN 2662-4435. S2CID 251498876.
- "The Arctic is warming four times faster than the rest of the world". Science Magazine. 2021-12-14. Retrieved 6 October 2022.
- Isaksen, Ketil; Nordli, Øyvind; et al. (15 June 2022). "Exceptional warming over the Barents area". Scientific Reports. 12. doi:10.1038/s41598-022-13568-5.
- Damian Carrington (2022-06-15). "New data reveals extraordinary global heating in the Arctic". The Guardian. Retrieved 7 October 2022.
- Francis, Jennifer A.; Vavrus, Stephen J. (2012). "Evidence linking Arctic amplification to extreme weather in mid-latitudes". Geophysical Research Letters. 39 (6): L06801. Bibcode:2012GeoRL..39.6801F. CiteSeerX 10.1.1.419.8599. doi:10.1029/2012GL051000. S2CID 15383119.
- Zielinski, G.; Mershon, G. (1997). "Paleoenvironmental implications of the insoluble microparticle record in the GISP2 (Greenland) ice core during the rapidly changing climate of the Pleistocene-Holocene transition". Bulletin of the Geological Society of America. 109 (5): 547–559. Bibcode:1997GSAB..109..547Z. doi:10.1130/0016-7606(1997)109<0547:piotim>2.3.co;2.
- Lue, J.-M.; Kim, S.-J.; Abe-Ouchi, A.; Yu, Y.; Ohgaito, R. (2010). "Arctic Oscillation during the Mid-Holocene and Last Glacial Maximum from PMIP2 Coupled Model Simulations". Journal of Climate. 23 (14): 3792–3813. Bibcode:2010JCli...23.3792L. doi:10.1175/2010JCLI3331.1.
- Mitchell, Daniel M.; Osprey, Scott M.; Gray, Lesley J.; Butchart, Neal; Hardiman, Steven C.; Charlton-Perez, Andrew J.; Watson, Peter (August 2012). "The Effect of Climate Change on the Variability of the Northern Hemisphere Stratospheric Polar Vortex". Journal of the Atmospheric Sciences. 69 (8): 2608–2618. Bibcode:2012JAtS...69.2608M. doi:10.1175/jas-d-12-021.1. ISSN 0022-4928.
- Masato, Giacomo; Hoskins, Brian J.; Woollings, Tim (2013). "Winter and Summer Northern Hemisphere Blocking in CMIP5 Models". Journal of Climate. 26 (18): 7044–7059. Bibcode:2013JCli...26.7044M. doi:10.1175/JCLI-D-12-00466.1.
- Liu, Jiping; Curry, Judith A.; Wang, Huijun; Song, Mirong; Horton, Radley M. (27 February 2012). "Impact of declining Arctic sea ice on winter snowfall". PNAS. 109 (11): 4074–4079. doi:10.1073/pnas.1114910109.
- Qiuhong Tang; Xuejun Zhang; Francis, J. A. (December 2013). "Extreme summer weather in northern mid-latitudes linked to a vanishing cryosphere". Nature Climate Change. 4 (1): 45–50. Bibcode:2014NatCC...4...45T. doi:10.1038/nclimate2065.
- Screen, J A (November 2013). "Influence of Arctic sea ice on European summer precipitation". Environmental Research Letters. 8 (4): 044015. Bibcode:2013ERL.....8d4015S. doi:10.1088/1748-9326/8/4/044015.
- Friedlander, Blaine (4 March 2013). "Arctic ice loss amplified Superstorm Sandy violence". Cornell Chronicle. Retrieved 7 January 2014.
- Walsh, Bryan (6 January 2014). "Polar Vortex: Climate Change Might Just Be Driving the Historic Cold Snap". Time. Retrieved 7 January 2014.
- Spotts, Pete (6 January 2014). "How frigid 'polar vortex' could be result of global warming (+video)". The Christian Science Monitor. Retrieved 8 January 2014.
- Jennifer Francis; Natasa Skific (1 June 2015). "Evidence linking rapid Arctic warming to mid-latitude weather patterns". Philosophical Transactions. 373 (2045): 20140170. Bibcode:2015RSPTA.37340170F. doi:10.1098/rsta.2014.0170. PMC 4455715. PMID 26032322.
- Mann, Michael E.; Rahmstorf, Stefan (27 March 2017). "Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events". Scientific Reports. 7: 45242. Bibcode:2017NatSR...745242M. doi:10.1038/srep45242. PMC 5366916. PMID 28345645.
- "Extreme global weather is 'the face of climate change' says leading scientist". The Guardian. 2018.
- Francis J; Vavrus S; Cohen J. (2017). "Amplified Arctic warming and mid latitude weather: new perspectives on emerging connections" (PDF). Wiley Interdisciplinary Reviews: Climate Change. 2017 Wiley Periodicals,Inc. 8 (5): e474. doi:10.1002/wcc.474.
- Fischetti, Mark (2017). "The Arctic Is Getting Crazy". Scientific American.
- Kretschmer, Marlene; Coumou, Dim; Agel, Laurie; Barlow, Mathew; Tziperman, Eli; Cohen, Judah (January 2018). "More-Persistent Weak Stratospheric Polar Vortex States Linked to Cold Extremes" (PDF). Bulletin of the American Meteorological Society. 99 (1): 49–60. Bibcode:2018BAMS...99...49K. doi:10.1175/bams-d-16-0259.1. ISSN 0003-0007. S2CID 51847061.
- Coumou, D.; Di Capua, G.; Vavrus, S.; Wang, L.; Wang, S. (2018-08-20). "The influence of Arctic amplification on mid-latitude summer circulation". Nature Communications. 9 (1): 2959. Bibcode:2018NatCo...9.2959C. doi:10.1038/s41467-018-05256-8. ISSN 2041-1723. PMC 6102303. PMID 30127423.
- Kim, Jin-Soo; Kug, Jong-Seong; Jeong, Su-Jong; Huntzinger, Deborah N.; Michalak, Anna M.; Schwalm, Christopher R.; Wei, Yaxing; Schaefer, Kevin (26 October 2021). "Reduced North American terrestrial primary productivity linked to anomalous Arctic warming". Nature Geoscience. 10: 572–576. doi:10.1038/ngeo2986.
- "Climate change: Arctic warming linked to colder winters". BBC News. 2 September 2021. Retrieved 20 October 2021.
- Cohen, Judah; Agel, Laurie; Barlow, Mathew; Garfinkel, Chaim I.; White, Ian (3 September 2021). "Linking Arctic variability and change with extreme winter weather in the United States". Science. 373 (6559): 1116–1121. Bibcode:2021Sci...373.1116C. doi:10.1126/science.abi9167. PMID 34516838. S2CID 237402139.
- Zou, Yofei; Rasch, Philip J.; Wang, Hailong; Xie, Zuowei; Zhang, Rudong (26 October 2021). "Increasing large wildfires over the western United States linked to diminishing sea ice in the Arctic". Nature Communications. 12. doi:10.1038/s41467-021-26232-9.
- Weng, H. (2012). "Impacts of multi-scale solar activity on climate. Part I: Atmospheric circulation patterns and climate extremes". Advances in Atmospheric Sciences. 29 (4): 867–886. Bibcode:2012AdAtS..29..867W. doi:10.1007/s00376-012-1238-1. S2CID 123066849.
- James E. Overland (December 8, 2013). "Atmospheric science: Long-range linkage". Nature Climate Change. 4 (1): 11–12. Bibcode:2014NatCC...4...11O. doi:10.1038/nclimate2079.
- Seviour, William J.M. (14 April 2017). "Weakening and shift of the Arctic stratospheric polar vortex: Internal variability or forced response?". Geophysical Research Letters. 44 (7): 3365–3373. Bibcode:2017GeoRL..44.3365S. doi:10.1002/2017GL073071. hdl:1983/caf74781-222b-4735-b171-8842cead4086. S2CID 131938684.
- Screen, James A. (15 June 2014). "Arctic amplification decreases temperature variance in northern mid- to high-latitudes". Nature Climate Change. 4 (7): 577–582. Bibcode:2014NatCC...4..577S. doi:10.1038/nclimate2268. hdl:10871/15095.
- van Oldenborgh, Geert Jan; Mitchell-Larson, Eli; Vecchi, Gabriel A.; de Vries, Hylke; Vautar, Robert; Otto, Friederike (22 November 2019). "Cold waves are getting milder in the northern midlatitudes". Environmental Research Letters. 14 (11). doi:10.1088/1748-9326/ab4867.
- Blackport, Russell; Screen, James A.; van der Wiel, Karin; Bintanja, Richard (September 2019). "Minimal influence of reduced Arctic sea ice on coincident cold winters in mid-latitudes". Nature Climate Change. 9 (9): 697–704. Bibcode:2019NatCC...9..697B. doi:10.1038/s41558-019-0551-4. hdl:10871/39784. S2CID 199542188.
- Blackport, Russell; Screen, James A. (February 2020). "Insignificant effect of Arctic amplification on the amplitude of midlatitude atmospheric waves". Science Advances. 6 (8): eaay2880. Bibcode:2020SciA....6.2880B. doi:10.1126/sciadv.aay2880. PMC 7030927. PMID 32128402.
- Streffing, Jan; Semmler, Tido; Zampieri, Lorenzo; Jung, Thomas (24 September 2021). "Response of Northern Hemisphere Weather and Climate to Arctic Sea Ice Decline: Resolution Independence in Polar Amplification Model Intercomparison Project (PAMIP) Simulations". Journal of Climate. 34 (20): 8445–8457. doi:10.1175/JCLI-D-19-1005.1.
- Paul Voosen (2021-05-12). "Landmark study casts doubt on controversial theory linking melting Arctic to severe winter weather". Science Magazine. Retrieved 7 October 2022.
- Smith, D.M.; Eade, R.; Andrews, M.B.; et al. (7 February 2022). "Robust but weak winter atmospheric circulation response to future Arctic sea ice loss". Nature Communications. 13. doi:10.1038/s41467-022-28283-y.
- Martin, Jonathan E. (14 April 2021). "Recent Trends in the Waviness of the Northern Hemisphere Wintertime Polar and Subtropical Jets". JGR Atmospheres. 126 (9). doi:10.1029/2020JD033668.
- Tenenbaum, Joel; Williams, Paul D.; Turp, Debi; Buchanan, Piers; Coulson, Robert; Gill, Philip G.; Lunnon, Robert W.; Oztunali, Marguerite G.; Rankin, John; Rukhovets, Leonid (23 June 2022). "Aircraft observations and reanalysis depictions of trends in the North Atlantic winter jet stream wind speeds and turbulence". Geophysical Research Letters. 148 (747). doi:10.1002/qj.4342.
- Osman, Matthew B.; Coats, Sloan; Das, Sarah B.; McConnell, Joseph R.; Chellman, Nathan (13 September 2021). "North Atlantic jet stream projections in the context of the past 1,250 years". PNAS. 118 (38). doi:10.1073/pnas.2104105118.
- "The Antarctic Ozone Hole Will Recover". NASA. June 4, 2015. Retrieved 2017-08-05.
- J.A. Pyle (1997). The Arctic and environmental change. CRC Press. pp. 42–44. ISBN 978-90-5699-020-6.
- Rolf Müller (2010). Tracer-tracer Relations as a Tool for Research on Polar Ozone Loss. Forschungszentrum Jülich. p. 47. ISBN 978-3-89336-614-9.
- K. Mohanakuma (2008). Stratosphere troposphere interactions: an introduction. Springer. p. 34. ISBN 978-1-4020-8216-0.
- "Arctic ozone loss at record level". BBC News Online. October 2, 2011. Archived from the original on October 3, 2011. Retrieved October 3, 2011.
- "Double vortex at Venus South Pole unveiled!". European Space Agency. Retrieved 2018-09-11.
- "Saturn's Bull's-Eye Marks Its Hot Spot". NASA. 2005. Retrieved January 8, 2014.
- "The science behind the polar vortex". NOAA.gov (NASA). 29 Jan 2019. Retrieved 31 Jan 2019.
- "What Is a Polar Vortex?". NOAA SciJinks.gov (NASA). Retrieved 31 Jan 2019.
- "What is the Polar Vortex?". US National Weather Service. Retrieved 31 Jan 2019.
- Nash, Eric R.; Newman, Paul A.; Rosenfield, Joan E.; Schoeberl, Mark R. (1996). "An objective determination of the polar vortex using Ertel's potential vorticity". Journal of Geophysical Research. 101 (D5): 9471–9478. Bibcode:1996JGR...101.9471N. doi:10.1029/96JD00066.
- Butchart, Neal; Remsberg, Ellis E. (1986). "The Area of the Stratospheric Polar Vortex as a Diagnostic for Tracer Transport on an Isentropic Surface". Journal of the Atmospheric Sciences. 43 (13): 1319–1339. Bibcode:1986JAtS...43.1319B. doi:10.1175/1520-0469(1986)043<1319:TAOTSP>2.0.CO;2.
- Schoeberl, Mark R.; Lait, Leslie R.; Newman, Paul A.; Rosenfield, Joan E. (1992). "The structure of the polar vortex". Journal of Geophysical Research. 97 (D8): 7859–7882. Bibcode:1992JGR....97.7859S. doi:10.1029/91JD02168.
- Coy, Lawrence; Nash, Eric R.; Newman, Paul A. (1997). "Meteorology of the polar vortex: Spring 1997". Geophysical Research Letters. 24 (22): 2693–2696. Bibcode:1997GeoRL..24.2693C. doi:10.1029/97GL52832. S2CID 128461145.
- Schoeberl, M.R.; Hartmann, D.L. (1991). "The Dynamics of the Stratospheric Polar Vortex and Its Relation to Springtime Ozone Depletions". Science. 251 (4989): 46–52. Bibcode:1991Sci...251...46S. doi:10.1126/science.251.4989.46. PMID 17778602.
- "Current map of arctic winds and temperatures at the 10 hPa level".
- "Current map of arctic winds and temperatures at the 70 hPa level".
- "Current map of arctic winds and temperatures at the 250 hPa level".
- "Current map of arctic winds and temperatures at the 500 hPa level".
- "Current map of antarctic winds and temperatures at the 10 hPa level".
- "Current map of antarctic winds and temperatures at the 70 hPa level".
- "Current map of antarctic winds and temperatures at the 250 hPa level".
- "Current map of antarctic winds and temperatures at the 500 hPa level".