Giant storms cause palpitations in Saturn’s atmospheric heartbeat

Posted by ap507 at Dec 13, 2017 02:05 PM |
Leicester scientist Dr Leigh Fletcher leads Cassini mission study into immense northern storms on Saturn
Giant storms cause palpitations in Saturn’s atmospheric heartbeat

Source: European Space Agency; VLT image of Saturn's giant vortex at mid-infrared wavelengths

Immense northern storms on Saturn can disturb atmospheric patterns at the planet’s equator, finds the international Cassini mission in a study led by Dr Leigh Fletcher from our Department of Physics and Astronomy and published in Nature Astronomy.

This effect is also seen in Earth’s atmosphere, suggesting the two planets are more alike than previously thought.

Despite their considerable differences, the atmospheres of Earth, Jupiter, and Saturn all display a remarkably similar phenomenon in their equatorial regions: vertical, cyclical, downwards-moving patterns of alternating temperatures and wind systems that repeat over a period of multiple years.

These patterns—known as the Quasi-Periodic Oscillation (QPO) on Saturn and the Quasi-Quadrennial Oscillation (QQO) on Jupiter, due to their similarities to Earth’s so-called Quasi-Biennial Oscillation (QBO)—appear to be a defining characteristic of the middle layers of a planetary atmosphere.

Earth’s QBO is regular and predictable, repeating every 28 months on average. However, it can be disrupted by events occurring at great distances from the equator of our planet—and a new study reveals that the same is true of Saturn’s QPO.

“These oscillations can be thought of as a planet’s heartbeat,” says Dr Fletcher who is lead author of the study and co-investigator of Cassini’s Composite Infrared Spectrometer (CIRS). “Cassini spotted them on Saturn about a decade ago, and Earth-based observations have seen them on Jupiter, too. Although the atmospheres of the distant gas giants may appear startlingly different to our own, when we look closely we start to discover these familiar natural patterns.”

Cassini observed Saturn from June 2004 until 15 September 2017 when the mission concluded by plunging into the gas planet's atmosphere. To better understand Saturn’s QPO, Fletcher and colleagues studied data from Cassini’s CIRS covering this entire time period.

Although the influence of Saturnian storms was known to be substantial, this study suggests an even wider influence than expected, and confirms a connection between Saturn’s QPO and remote, distinct events occurring elsewhere in the planet’s atmosphere.

“We became especially excited when we compared this palpitation on Saturn to one observed in Earth’s QBO in 2016: it was disturbed in a similar way by waves carrying momentum from Earth's northern hemisphere to the equator,” adds Fletcher. “That disruption was unprecedented in over 60 years of monitoring the QBO—and yet we were lucky enough to capture a similar behaviour at work on Saturn with Cassini.”

On Earth, this relationship between distant events in a planet’s climate system is known as teleconnection. Meteorological patterns across the globe are known to be delicately linked together, and can affect one another quite significantly. A key example of this is the El Niño Southern Oscillation, which can influence temperatures and climate patterns across the Earth.