A close study of data from the past 40 years has revealed strange temperature fluctuations in Jupiter’s clouds.
According to a wealth of information collected by both ground-based and space-based telescopes, Jupiter’s upper troposphere exhibits regular temperature fluctuations that do not appear to be linked to any seasonal variation.
This surprising and intriguing discovery could help scientists finally understand the gas giant’s strange weather.
“We have solved part of the puzzle now, which is that the atmosphere exhibits these natural cycles,” says Leigh Fletcher of the University of Leicester in the UK.
“To understand what drives these patterns and why they occur at these particular timescales, we need to explore both above and below the cloud layers,” he continued.
Strange temperature fluctuations found in Jupiter data
It should come as no surprise to anyone that Jupiter, the largest planet in the Solar System, is very different from our wonderful habitable world. Jupiter is buffeted by wild winds, cloaked in thick layers of clouds, and marred by ferocious storms that can grow to sizes larger than Earth. Its extreme weather is so different that scientists have struggled to understand it, he writes Science Alert.
We know that Jupiter is surrounded by alternating bands of light and dark clouds known as zones and belts that rotate around the planet in opposite directions. We also know from infrared images that the darker belts are warmer, at least in part because the clouds are thinner, allowing more heat to escape from the planetary interior.
Another interesting thing about Jupiter is that it doesn’t have much of an inclination. The axis on which the planet rotates is only 3 degrees relative to its orbital plane around the Sun. Here on Earth, and on other planets like Mars and Saturn, a strong axial tilt (23.4 degrees for Earth) directs the poles toward or away from the Sun, causing seasonal temperature fluctuations.
Scientists never expected Jupiter to experience significant cycles of temperature variation, but until now, long-term data sets of the planet’s heat profile have not been available to verify whether this was the case.
What does the data show?
Now, data from instruments aboard the Voyager and Cassini spacecraft and NASA’s Very Large Telescope, Subaru Telescope and Infrared Telescope Facility have given a team led by planetary scientist Glenn Orton of NASA’s Jet Propulsion Laboratory decades of thermal data to work with.
To their surprise, the researchers found temperature fluctuations with periodicities of 4 or 7 to 9 years and 10 to 14 years, depending on the latitude bands. These appear disconnected, they found, from seasonal variations in temperature.
However, there is some internal consistency: as temperatures rise at certain latitudes in the Northern Hemisphere, they fall at corresponding latitudes in the Southern Hemisphere, particularly at 16, 22, and 30 degrees. It is as if Jupiter is a mirror of itself, divided by the equator, maintaining thermal balance.
“That was the most surprising thing,” says Orton.
“We found a link between how temperatures varied at very distant latitudes. It’s similar to a phenomenon we see on Earth, where weather and climate patterns in one region can have a noticeable influence on weather elsewhere, with patterns of variability seemingly ‘teleconnected’ over long distances through the atmosphere,” adds the researcher.
The cause of these temperature fluctuations is not known
It’s not clear what causes or links these temperature fluctuations to each other, but a clue can be found higher up in Jupiter’s atmosphere, in the clear stratospheric layer that sits above the cloudy troposphere. At Jupiter’s equator, temperature variations in the troposphere are matched by an opposite variation in the stratosphere. This suggests that whatever happens at higher altitudes influences what happens below, or vice versa.
And whatever the cause, this study is a very important piece of the puzzle that could one day help scientists be able to accurately understand and predict the weather on Jupiter.
“Measuring these temperature changes and periods over time is a step toward eventually having a complete weather forecast for Jupiter if we can connect cause and effect in the planet’s atmosphere,” says Fletcher.
“And the big question is whether we can one day extend this to other giant planets to see if similar patterns emerge,” he concluded.
The research was published in Nature Astronomy.