A Sober Look At The Northern Polar Vortex

Image Credit NASA – Polar Vortex on Venus

WUWT Regular “Just The Facts”

Currently there is a lot of media hype about the Polar Vortex over North America, but little in the way of coherent explanation as to what a Polar Vortex is and how it affects Earth’s temperature. As such, a Polar Vortex is “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 “A polar vortex is a persistent, large-scale cyclone located near one or both of a planet’s geographical poles.” “The vortex is most powerful in the hemisphere’s winter, when the temperature gradient is steepest, and diminishes or can disappear in the summer.” Wikipedia In addition to those on Earth, Polar Vortices also have been sighted on Venus, Mars, Jupiter , Saturn and Saturn’s Moon Titan.

“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

So with that background, let’s take a look at the Polar Vortex currently over North America. Starting at 10 hPa/mb – Approximately 31,000 meters (101,700 feet) here we have a Height Analysis showing the low pressure area;

a Temperature Analysis showing the cold area;

Zonal Mean Temperatures showing the cold area from a global perspective;

a wide perspective Wind Animation and more focused Wind Animation showing the motion of the Vortex,

and Ozone Mixing Ratio map showing the “Ozone Hole” within it:

Now we are going to travel down the Polar Vortex in several steps, so here’s another Height Analysis showing the low pressure area at 30 hPa/mb – Approximately 23,700 meters (77,800 feet);

a Temperature Analysis showing the cold area;

Zonal Mean Temperatures showing the cold area from a global perspective;

and Ozone Mixing Ratio map showing the “Ozone Hole” within the Vortex:

Here’s  a Height Analysis showing the low pressure area at 70 hPa/mb – Approximately 18,000 meters (59,000 feet);

a Temperature Analysis showing the cold area;

Zonal Mean Temperatures showing the cold area from a global perspective;

a wide perspective Wind Animation and more focused Wind Animation showing the motion of the Vortex,;

and Ozone Mixing Ratio map showing a slight “Ozone Hole” within it:

And here’s here we have a Height Analysis showing the low pressure area at 100 hPa/mb – Approximately 15,000 meters (49,000 feet);

a Temperature Analysis showing the cold area;

Zonal Mean Temperatures showing the cold area from a global perspective;

and Ozone Mixing Ratio map showing a slight “Ozone Hole” within the Vortex:

Per this Northern Hemisphere – Vertical Cross Section of Geopotential Height Anomalies you can see that the Polar Vortex currently extends to approximately 100 hPa/mb:

also reflected in this Northern Hemisphere – Area Where Temperature is Below 195K or -78C:

So why is it so cold in North America right now? Per Global – 10-hPa/mb Height Temperature Anomalies – Atmospheric Temperature Anomalies At Approximately 31,000 meters (101,700 feet);

it appears that that we are having an [Upper Stratosphere Lower Mesosphere (USLM) Disturbance] that could lead to a Sudden Stratospheric Warming growing over East Asia, i.e. “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 degrees Celsius over a few days can occur. The Arctic vortex is elongated in shape, with two centres, one roughly over Baffin Island in Canada and the other over northeast Siberia. In rare events, the vortex can push further south as a result of axis interruption, see January 1985 Arctic outbreak.” Wikipedia ”The January 1985 Arctic outbreak was a meteorological event, the result of the shifting of the polar vortex further south than is normally seen. Blocked from its normal movement, polar air from the north pushed into nearly every section of the eastern half of the United States, shattering record lows in a number of states.” Wikipedia This BBC Article and Video are helpful in understanding Sudden Stratospheric Warmings. (Note that the text within the [brackets] above has been added and the struck-through removed to correct the article based upon learnings from this comment and this comment below.)

In terms of claims that “US polar vortex may be example of global warming” Guardian and “Polar Vortex: Climate Change Could Be the Cause of Record Cold Weather” Time, these appear to be unsupported conjecture as:

“Many atmospheric general circulation models (GCMs) and chemistry–climate models (CCMs) are not able to reproduce the observed polar stratospheric winds in simulations of the late 20th century. Specifically, the polar vortices break down too late and peak wind speeds are higher than in the ERA-40 reanalysis. Insufficient planetary wave driving during the October–November period delays the breakup of the southern hemisphere (SH) polar vortex in versions 1 (V1) and 2 (V2) of the Goddard Earth Observing System (GEOS) chemistry–climate model, and is likely the cause of the delayed breakup in other CCMs with similarly weak October-November wave driving.”

“In the V1 model, the delayed breakup of the Antarctic vortex biases temperature, circulation and trace gas concentrations in the polar stratosphere in spring. The V2 model behaves similarly (despite major model upgrades from V1), though the magnitudes of the anomalous effects on springtime dynamics are smaller.”

“Clearly, if CCMs cannot duplicate the observed response of the polar stratosphere to late 20th century climate forcings, their ability to simulate the polar vortices in future may be poor.”

Assessment and Consequences of the Delayed Breakup of the Antarctic Polar Vortex in Chemistry-Climate Models Hurwitz et al., 2009

“It is unclear how much confidence can be put into the model projections of the vortices given that the models typically only have moderate resolution and that the climatological structure of the vortices in the models depends on the tuning of gravity wave parameterizations.

Given the above outstanding issues, there is need for continued research in the dynamics of the vortices and their representation in global models.”

Stratospheric Polar Vortices, Waugh et al. 2010

To learn more about Polar Vortices please visit the WUWT Polar Vortex Reference Page.