University of Oulu

Vokhmyanin, M., Asikainen, T., Salminen, A., & Mursula, K. (2023). Long-term prediction of sudden stratospheric warmings with geomagnetic and solar activity. Journal of Geophysical Research: Atmospheres, 128, e2022JD037337.

Long-term prediction of sudden stratospheric warmings with geomagnetic and solar activity

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Author: Vokhmyanin, Mikhail1; Asikainen, Timo1; Salminen, Antti1;
Organizations: 1Space Physics and Astronomy Research Unit, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 4.1 MB)
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Language: English
Published: American Geophysical Union, 2023
Publish Date: 2023-11-07


The polar vortex is a strong jet of westerly wind which forms each winter around the polar stratosphere. Sometimes, roughly every other winter, the polar vortex in the Northern Hemisphere experiences a dramatic breakdown and associated warming of the polar stratosphere. Such events are called sudden stratospheric warmings (SSWs) and they are known to have a significant influence on ground weather in Northern Eurasia and large parts of North America. Typically, these events are thought to occur due to planetary waves propagating to the stratosphere where they may disrupt the vortex. Here, we show that the SSW probability depends significantly on a favorable combination of geomagnetic and solar activity and the phase of the Quasi-Biennial Oscillation (QBO). Using logistic regression models, we find that more SSWs occur when early-winter geomagnetic activity (aa index) is low and QBO winds are easterly and when solar activity (F10.7 index) is high and QBO winds are westerly. We then examine the possibility of using these results to predict the occurrence probability of SSWs with several months lead time and evaluate the optimal lead times for all variables using cross-validation methods. As a result, we find that the SSW probability can be predicted rather well and we can issue a probabilistic SSW prediction for the coming winter season with a success ratio of about 86% already in the preceding August. The results presented here are an important step toward improving the seasonal predictability of wintertime weather using information about solar and geomagnetic activity.

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Series: Journal of geophysical research. Atmospheres
ISSN: 2169-897X
ISSN-E: 2169-8996
ISSN-L: 2169-897X
Volume: 128
Issue: 6
Article number: e2022JD037337
DOI: 10.1029/2022JD037337
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: We acknowledge the financial support by the Academy of Finland to the PROSPECT (project 321440), and by the University of Oulu and The Academy of Finland PROFI4 (Grant 318930). Antti Salminen acknowledges the funding from the Finnish Cultural Foundation (Grant 00200976).
Academy of Finland Grant Number: 321440
Detailed Information: 321440 (Academy of Finland Funding decision)
Copyright information: © 2023. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.