Why Jupiter's jet stream reverses course on a predictable schedule?

Jan. 17, 2018, 12:03 p.m. By: Pranjal

Jupiter's Red Spot

It is a well-known mystery among the scientist regarding the reversal of jet stream course on Jupiter. But, finally, scientists have succeeded in solving this mystery. Jupiter's jet stream regularly reverses course which is similar to a clockwork. This can help scientists in understanding similar equatorial jet stream oscillations found on Earth and Saturn.

The recent research has revealed that gravity waves are the primary driver of the reversal of Jupiter's equatorial jet stream. The equatorial jet stream was first discovered after watching ash from the 1883 eruption of the Krakatoa volcano being blown from east-to-west. The stratospheric current was later confirmed by hot air balloons.

On earth, jet stream begins in the lower stratosphere and moves toward the upper troposphere. These current reverses its course every 28 months. This phenomenon is known as quasi-biennial oscillation. However, in case of Jupiter, it is known as quasi-quadrennial oscillation as each phase lasts 4 earth years.

With the latest advancement in technology and NASA's Infrared Telescope Facility, scientists were able to capture the higher resolutions images of the current which expands over a large area and for a longer time span. These measurements were able to probe thin vertical slices of Jupiter's atmosphere. The recent measurement was much improved over the previous one as those data sets had the poor resolution because of which the signals smeared out over a large section of the atmosphere.

Scientists have also succeeded in building an atmospheric model using data collected during the comprehensive survey of Jupiter's quasi-quadrennial oscillation. The simulations carried out during experiment suggested that gravity waves produced in the lower atmosphere are propagated upward where they cause the equatorial jet stream to reverse course. Scientists also believe that gravity waves are also a major driver of Earth's quasi-biennial oscillation reversal but those aren’t powerful enough to power the oscillation alone.