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    Climate change playing role in late-winter shift in polar vortex

    11/16/2016, 9:51:49 PM

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    New research published in the journal Nature Climate Change has found that the wintertime Arctic stratospheric polar vortex has weakened over the past three decades.

    The result of this weakening is an increased probability of cold surface air from the high latitudes shifting southward into the middle latitudes.


    590x331_11030046_1415900805524_wps_6_the_atmosphere_is_prepari


    Over the past three decades there has also been a rapid warming of the surface air over the Arctic region and northeastern Canada.

    According to the report, it is unknown if the location of the polar vortex has also experienced a persistent change in response to Arctic climate change

    The researchers are also unsure if the changes in the position of the polar vortex will have implications for the climate system.

    Polar stratospheric ozone depletion and the Arctic Oscillation (AO) may also have impacts on the vortex position.

    The research team found that the polar vortex shifted persistently from North America and towards the Eurasian continent during the month of February over the past three decades.

    The main cause for this shift was likely due to Arctic sea ice loss, which caused an enhancement of zonal wavenumber-1 waves, especially over the Barents and Kara seas.

    A possible secondary cause is an increase in snow cover over the Eurasian Continent, especially during the fall months.

    This shift in the polar vortex enhanced wintertime cooling over parts of the Eurasian continent and North America. This has partly offset the tropospheric climate warming over these continents during the past three decades.

    The left image below shows the typical position of the polar vortex over the Arctic region. The right image shows a piece of the polar vortex shifted much farther to the south, which brings cold air into the middle latitudes.

    590x311_11030048_vortex-diagram


    In closing, the researchers believe that this change in the polar vortex could lead to a colder late winter/early spring climate over some parts of the continents, which partly offsets the underlying climate warming during these seasons.

    The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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    Global climate change