When the “Beast from the East” brought cold temperatures and heavy snowfall to western Europe in February and March 2018, a lot of people were quick to link the extreme weather to a sudden stratospheric warming (SSW) that had recently occurred. CLEX researchers found there was a surprising lack of research on the relationship between SSWs and climate extremes in Europe using observations, so they sought to look at this in more detail to see if this link can really be made.
SSWs are rapid warming events that occur tens of kilometres above the Earth’s surface in the Northern Hemisphere. They are often associated with cold winter weather at the surface in the Northern Hemisphere, but prior to our study, the connection between SSWs and cold weather had been made using reanalyses and models rather than observational data. The researchers performed the first comprehensive analysis of the link between SSWs and climate extremes in Europe.
They found winters with SSWs are substantially colder than average in areas like Scandinavia. Below‐average temperatures tend to precede SSW events, but the intensity of cold extremes, such as the coldest night of the month, tends to be strongest after the SSW event. This is unusual as when we study other climate teleconnections we usually see similar patterns in the mean and extreme responses.
The 2018 SSW, which helped motivate the study, exhibited stronger cold anomalies in extreme indices over northwest Europe than any SSW in the 1979–2016 period. Through this analysis they found a link between SSWs and European wintertime climate extremes.
- Paper: King, A. D., A. H. Butler, M. Jucker, N. O. Earl, and I. Rudeva, 2019: Observed relationships between Sudden Stratospheric Warmings and European climate extremes. J. Geophys. Res.- Atmos., 124, 13943-13961, doi: 10.1029/2019JD030480.