Every winter in the northern hemisphere, cold winds circulate around the Arctic like water around a bank. It’s an annual weather pattern that meteorologists watch with concern – any major changes could indicate Europe is on its way to a dangerous cold snap. For now, that wind is tearing in two.
Researchers from the universities of Bristol, Exeter, and Bath have come up with a new way to predict the indirect effects of the various changes in the elevated main air stream in the region. Stratosphere, 10 to 50 kilometers (6 to 30 miles).
Ironically, this cold is caused by a sudden explosion of heat that seeps into rotating currents through a window for only 24 to 48 hours.
As it warms up to 40 ° C, the vortex undergoes some rapid changes, changing its course or separating dramatically into small eddies that move against the surrounding atmosphere.
The results can be devastating. Just a few years ago, a sudden Stratospheric Up (SSW) event drove the frozen polar air from Siberia to Europe, giving rise to a snow-filled cell of high pressure, which the media called Beast of the east.
The shock of icy weather was centered over Scandinavia, casting a frozen shadow in the far west of the UK Contribute to transportation chaos And even a number of deaths.
However, not all transitions in this polar vortex end with freezing conditions. Two years ago, a warming in the stratospheric polar winds preceded one of the warmest winter days in recorded UK history.
Knowing which aberrations are harbingers of winter’s rage, and which ones will fade, will go a long way in making the weather forecast more accurate.
Surprisingly, stratospheric greenhouse events themselves are not entirely rare, with records indicating that about half a dozen of them occur in the Arctic vortex every decade.
“While a very cold weather event is not certain, about two-thirds of cold weather temperatures have a significant impact on surface weather,” Says Richard Hall, meteorologist at the University of Bristol and lead author of the new study.
Observations dating back more than six decades have provided researchers with 40 patterns of oscillations and defections in the Arctic stratospheric vortex, which inform a tracking algorithm that tries to predict the impact of each type of change on weather systems across the Northern Hemisphere. .
The results indicate that any time the polar vortex splits into two smaller winds, we can expect more intense cooling events, compared to other SSW anomalies.
It’s a timely result, with changes to air currents expected over the weekend.
“As expected, atmospheric observations now show that the stratosphere in the Arctic is undergoing a sudden warming event associated with the weakening of the polar stratosphere,” Says Adam Skiff, Head of Long Range Forecasting at the UK Met Office.
Moreover, the change has all the hallmarks of a more severe type of SSW, which means there is a good chance that the expected temperature drop will be significant.
Having thoughtful climate models definitely helps improve the odds of knowing what to expect. But while modeling on this scale benefits from improved algorithms, there is still room for a lot of uncertainty when it comes to coding down the finer details in the coming days.
Strangely, it may turn out that Europe is sweating instead of shivering.
The UK saw a record high in winter warmth after the summer winters in February 2019, so the Met Office is not ruling out the possibility of a similar heat in the coming weeks.
Although the long cold and snow wave that occurred in February and March of 2018 – which the British media called the ‘Beast from the East’ – were associated with a sudden rise in the stratosphere, the record warmth of February 2019 was also followed by an event. , Says Meteorologist Matthew Lienert.
We have some way to go before we can confidently promise the way the weather will go in the wake of these polar changes.
But tools like this new algorithm will improve guesswork possibilities, and will continue to do so as we learn more about our atmosphere.
“Despite this progress, many questions remain about the mechanisms that cause these dramatic events, and how they might affect the surface, so this is an exciting and important area for future research,” Says Mathematician William Seavey of the University of Exeter.
This research was published in JGR Ambiance.