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

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.