University of Oulu

Salminen, A., Asikainen, T., Maliniemi, V., & Mursula, K. ( 2020). Dependence of sudden stratospheric warmings on internal and external drivers. Geophysical Research Letters, 47, e2019GL086444.

Dependence of sudden stratospheric warmings on internal and external drivers

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Author: Salminen, A.1; Asikainen, T.1; Maliniemi, V.2;
Organizations: 1ReSoLVE Centre of Excellence, Space Climate Research Unit, University of Oulu, Oulu, Finland
2Birkeland Centre for Space Science, Department of Physics and Technology, University of Bergen, Bergen, Norway
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.8 MB)
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Language: English
Published: American Geophysical Union, 2020
Publish Date: 2020-08-29


A sudden stratospheric warming (SSW) is a large‐scale disturbance of the wintertime stratosphere, which occurs especially in the Northern Hemisphere. Earlier studies have shown that SSW occurrence depends on atmospheric internal factors and on solar activity. We examine SSW occurrence in northern winters 1957/1958–2016/2017, considering several factors that may affect the SSW occurrence: Quasi‐Biennial Oscillation (QBO), El Niño–Southern Oscillation (ENSO), geomagnetic activity, and solar radiation. We confirm the well‐known result that SSWs occur more often in easterly QBO phase than in westerly phase. We show that this difference depends on how the QBO phase is determined. We find that the difference in SSW occurrence between easterly and westerly QBO winters strengthens (weakens) if geomagnetic activity or solar activity is low (high), or if the ENSO is in a cold (warm) phase. In easterly QBO phase significantly more SSWs occur during low geomagnetic activity than high activity.

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Series: Geophysical research letters
ISSN: 0094-8276
ISSN-E: 1944-8007
ISSN-L: 0094-8276
Volume: 47
Issue: 5
Article number: e2019GL086444
DOI: 10.1029/2019GL086444
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 ReSoLVE Center of Excellence (Project 307411) and to the PROSPECT project (Project 321440) and by the Kvantum institute of the University of Oulu to CAESAR project. V.M. was funded by the Norwegian Research Council under contract 223252/F50.
Academy of Finland Grant Number: 307411
Detailed Information: 307411 (Academy of Finland Funding decision)
321440 (Academy of Finland Funding decision)
Copyright information: © 2020. American Geophysical Union.