Disruption of Saturn’s quasi-periodic equatorial oscillation by the great northern storm

Journal article

The equatorial middle atmospheres of the Earth 1 , Jupiter 2 and Saturn 3,4 all exhibit a remarkably similar phenomenon-a vertical, cyclic pattern of alternating temperatures and zonal (east-west) wind regimes that propagate slowly downwards with a well-defined multi-year period. Earth's quasi-biennial oscillation (QBO) (observed in the lower stratospheric winds with an average period of 28 months) is one of the most regular, repeatable cycles exhibited by our climate system 1,5,6 , and yet recent work has shown that this regularity can be disrupted by events occurring far away from the equatorial region, an example of a phenomenon known as atmospheric teleconnection 7,8 . Here, we reveal that Saturn's equatorial quasi-periodic oscillation (QPO) (with an ~15-year period 3,9 ) can also be dramatically perturbed. An intense springtime storm erupted at Saturn's northern mid-latitudes in December 2010 10-12 , spawning a gigantic hot vortex in the stratosphere at 40° N that persisted for three years 13 . Far from the storm, the Cassini temperature measurements showed a dramatic ~10 K cooling in the 0.5-5 mbar range across the entire equatorial region, disrupting the regular QPO pattern and significantly altering the middle-atmospheric wind structure, suggesting an injection of westward momentum into the equatorial wind system from waves generated by the northern storm. Hence, as on Earth, meteorological activity at mid-latitudes can have a profound effect on the regular atmospheric cycles in Saturn's tropics, demonstrating that waves can provide horizontal teleconnections between the phenomena shaping the middle atmospheres of giant planets.

Authors: Fletcher, L; Guerlet, S; Orton, G; Cosentino, R; Fouchet, T

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Publishing Group
• Journal: Nature Astronomy
• Volume: 1
• Issue: 11
• Pages: 765-770
• Publication date: 2017-10-23
• Acceptance date: 2017-09-05
• DOI: 10.1038/s41550-017-0271-5
• EISSN: 2397-3366
• ISSN: 2397-3366
• Keywords: Journal Article