With no Solid Surface, the Atmosphere of Jupiter Behaves Quite Differently Than Earth

Jupiter’s atmosphere has plenty of distinct features, including lightning and the Great Red Spot.  But the underlying processes that drive these features are less well understood, as the physics of the gases that make up Jupiter’s atmosphere is complicated.  A team of scientists from all over the globe has found a familiar process in all the chaos, though.  They think a process that happens here on Earth might be happening on a grander scale at Jupiter.

The first hints at that process were visible when looking at one of the most common chemicals in Jupiter’s atmosphere – ammonia. Ammonia is extremely common in Jupiter’s atmosphere, but there are variations in its concentration levels that are hard to explain using traditional terrestrial weather modeling.  To try to piece together what is causing these variations in ammonia, the research team turned to new data collected by Juno.  

Juno has a tool known as the Jovian Infrared Auroral Mapper (JIRAM).  It tracks auroral activity in Jupiter’s upper atmosphere, including lighting.  The data it provided pointed the research team to a better understanding of where the ammonia anomalies appeared.

They then turned to another Juno instrument known as the Microwave Radiometer (MWR).  This one specializes in seeing beneath atmospheric layers of gas giants, which it did with Jupiter.  While doing so, it noticed that the upper layer of the atmosphere seemed to interact regularly with lower layers, causing a kind of vertical flow pattern that is seen on Earth as a form of what is known as a Ferrell cell.

A “Ferrell Cell”, is a type of wind pattern around Earth’s meridians.  On our planet, there are only two Ferrell cells, one in each hemisphere.  They are sandwiched between the Hadley cells near the equator and the Polar cells near each pole.  Typically their job is to spin “counter” to the other cells that would allow wind to interact in a sort of zig-zag pattern through the hemisphere.  

Jupiter, on the other hand, has eight of these patterns spread across each hemisphere. The wind patterns of these cells may be responsible for the color bands on Jupiter, which run from east to west. They align with the expected boundaries of these analog Ferrel cells.

While there are some similarities to the Earth analog, the flow pattern was different on Jupiter than on Earth.  Despite its massive size, the gas giant lacks a stable surface layer to bound the force of the wind.    However, according to data from MWR, it might have a “stable” layer a few kilometers down in the atmosphere that could act similarly for the gas flow pattern as it does here on Earth.

If that is indeed the case, Jupiter’s atmosphere might be even more complex than initially thought.  Preliminary modeling points to that being the truth – something is acting as a drag on the air rotating in these circular patterns. It is not clear what that might be, but the best way to figure it out is to simulate the overall process.  The research team modeled a formative process of the ammonia anomalies and included factors such as gaseous diffusion and precipitation of the ammonia itself in the form of slush balls.   Adding in something equivalent to extremely vertical Ferrell cells fit the model the best.

All of these discoveries would not have been possible without data from Juno, which has been orbiting Jupiter and its moons for the past 5 years. But that doesn’t mean Jupiter is the only planet to experience these kinds of atmospheric turbulence.  The Sun might also be harboring these types of complicated weather patterns.  Scientists won’t know until they look, but preliminary data to test that hypothesis could be on its way with the Solar Orbiter and Parker both hoping to start collecting data soon.  With luck, more of these types of discoveries await us on the biggest object in our own solar system.

Learn More:
arXiv – Evidence for multiple Ferrel-like cells on Jupiter
UT – What is the Weather like on Jupiter?
UT – What are Temperatures Like on Jupiter?
UT – Here’s Jupiter from Juno’s Latest Flyby

Lead Image:
Cross section of Jupiter’s different atmospheric cells as described in the paper.
Credit – Duer et al.