https://twitter.com/DrAHButler/status/1453121782244851717/photo/1
Thought I'd update this plot since I'm getting retweets of older versions. I've added/changed some things; here using NDJ QBO 50 hPa and Nino 3.4 from CPC. Solid dots = corresponding winters (Nov-Mar) with SSWs, empty dots = winters with no SSWs. SSW = sudden strat warming.
I've added the frequency of #SSWs for each quadrant (QBO +/-, Nino 3.4 +/- 0.5), and the barplots show the frequency of SSWs in each "bin" of either Nino 3.4 or QBO phase. The black dashed line on the histogram shows the overall frequency 0.63 SSWs/yr in JRA-55 reanalysis.
This shows we get the most #SSWs during La Nina winters and easterly #QBO. But this combination also happens by far the least (only 6 NDJs in a 64 year record!). It also shows that you get increased SSWs in both phases of ENSO relative to neutral, and for strong easterly QBOs.
Currently, it's looking possible to get the elusive #LaNina, easterly #QBO this winter, but it's hard to say for sure because QBO at 50 hPa is still westerly and taking its sweet time changing to easterly.
The final takeaway from this figure is that it's possible to get a #SSW in any phase of ENSO/QBO. It's just more likely in some phases compared to others.
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Tweet van stratofreak & profesional Amy Butler.
-> kans op een SSW is in een La Nina/ El Nino groter dan in een neutrale setting
-> De meeste SSWs tijdens La Nina winters met een oostelijke QBO. Zeldzame combinatie.
-> Ze wijst erop, dat het kan maar QBO op 50 hPa nog steeds westelijk is
