The video captures an atmospheric extreme event, a so-called sudden stratospheric warming (SSW) event, which occurred on February 12, 2018.
It is visualized through potential vorticity above the North Pole, a measure for the presence of anticlockwise rotation in the atmosphere of the Northern Hemisphere, at the 10hPa level, i.e. at about 30km above the Earth’s surface.
The event consists of a split of the winter polar vortex into two separate vortices that subsequently interact with each other. These events occur about 6 times per decade and can dominate the flow of the Northern Hemisphere middle atmosphere for months. They are best known for having long-lasting impacts on the weather at the surface, in particular these events can lead to persistent cold spells over Europe, as observed after the event pictured in the video.
SSW events are a matter of active research at ETH Zurich in the group of Daniela Domeisen, as much is unknown about their causes, their predictability, and their impacts. Although the events themselves are not predictable more than a few days in advance due to their complex dyamical behavior, they can have lasting impacts on winter weather over Europe, which makes them an important puzzle piece for long-range weather forecasting. In addition, there is an ongoing international debate about potential changes in frequency of these events with climate change, which could have significant impacts on changes in winter weather for Europe.
Video credits and copyright:
Alexander Wollert (University of Applied Sciences Düsseldorf), Daniela Domeisen (ETH Zurich)