Every winter in the Northern Hemisphere, a cold wind orbits the North Pole like water around a drain. It’s an annual weather pattern meteorologists look forward to. Any notable changes suggest Europe is in for a serious cold snap. Currently, that wind is ripping in two.
Researchers from the Universities of Bristol, Exeter, and Bath have formulated a new method to anticipate the knock-on effects of different changes to this major air current high up in the stratosphere, 10 to 50 kilometres (6 to 30 miles) overhead.
Ironically, the reason for this chill is a sudden burst of heat seeping into the whirling currents over a window of just 24 to 48 hours.
With its temperature surging by as much as 40 degrees Celsius, the whirlwind faces some rapid changes, changing course or strikingly breaking apart into daughter vortices that shove against the surrounding atmosphere.
The results can be disastrous. A few years back, a sudden stratospheric warming (SSW) event nudged frigid polar air from Siberia into Europe, delivering a snow-laden cell of high pressure, dubbed by the media as The Beast from the East.
Centred over Scandinavia, the shock of icy weather cast a frozen pall as far west as the UK, contributing to transport chaos and even several deaths.
Observations of more than six decades have provided the researchers with 40 examples of wobbles and split in the northern stratospheric polar vortex, which communicates a tracking algorithm that attempts to forecast the impact each kind of change will have on weather systems across the northern hemisphere.
The results reveal that any time the polar vortex splits into two smaller winds we can witness more severe cooling events, compared with other SSW anomalies.
The change has all the attributes of the more deadly SSW, meaning there’s a every possibility that the predicted drop in temperature will be crucial.
Being informed about climate models definitely helps improve the odds of knowing what to expect. But while modelling on this scale benefits from improved algorithms, there’s still possibility of uncertainty when it comes to nailing down the exact details in coming days.
Surprisingly, it may even turn out that Europe sweats instead of shivers.
But tools like this new algorithm will help to guess accurately and continue to do so the more we learn about our atmosphere.