Knowledge of the tropospheric temperature field and its fluctuations is crucial for planetary climatology. A dynamic relationship between tropospheric and stratospheric temperatures, as well as non-seasonal periodic behavior, has been suggested by previous studies of Jupiter. However, these observations either used sparse sampling or were made over periods shorter than Jupiter’s orbit.

New research breaks new ground by tracking temperatures in Jupiter’s upper troposphere. The research, conducted over four decades by combining NASA spacecraft data with ground-based telescope observations, discovered surprising patterns in the temperature changes of Jupiter’s bands and zones.

Like Earth’s, Jupiter’s troposphere is where clouds develop and storms rage. To understand this weather activity, scientists need to examine several characteristics, such as wind, pressure, humidity and temperature. Since NASA’s Pioneer 10 and 11 missions in the 1970s, scientists have known that Jupiter’s brighter and whiter bands, known as zones, are places with colder temperatures. In contrast, the planet’s deeper brownish-red bands, known as belts, are locations of warmer temperatures.

But more datasets were needed to understand how temperatures vary over the long term. Scientists in this study examined images of the bright infrared glow (invisible to the human eye) rising from warmer regions of the atmosphere and directly measuring Jupiter’s temperatures above the colorful clouds. These images were collected regularly over three orbits of Jupiter around the sun, each lasting 12 Earth years.

They found that Jupiter’s temperatures fluctuate over specific time periods that are not linked to the seasons or other cycles now known to science. Scientists didn’t expect temperatures on Jupiter to change in such predictable cycles because Jupiter has weak seasons and is tilted off its axis by only 3 degrees, compared to Earth’s jaunty 23.5 degrees.

The research also revealed a puzzling connection between temperature changes in places thousands of miles away: When temperatures rose at specific latitudes in the Northern Hemisphere, they fell at the same latitudes in the Southern Hemisphere — like a mirror image across the equator.

NASA noted, “Scientists began this research in 1978. During their research, several times a year they wrote proposals to gain observation time at three major telescopes around the world: the Very Large Telescope in Chile and NASA’s Infrared Telescope Facility and the Subaru Telescope at Maunakea observatories in Hawaii.

“During the first two decades of research, scientists took turns traveling to those observatories to collect the information about temperatures that would eventually allow them to connect the dots. Then came the hard part: combining several years of observations from different telescopes and scientific instruments to look for patterns. Accompanying these veteran scientists on their long-term study were several undergraduate interns, none of whom had been born when the study began.

Glenn Orton, a senior research scientist at NASA’s Jet Propulsion Laboratory and lead author of the study, said: “We found a connection 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 impact on weather elsewhere, with the variability patterns seemingly being ‘teleconnected’ over great distances through the atmosphere.”

Co-author Leigh Fletcher of the University of Leicester in England said: “We have now solved part of the puzzle: the atmosphere shows these natural cycles. We need to examine both above and below the cloudy layers to understand what drives these patterns and why they occur on these specific timescales.”

Scientists hope the study will eventually help them predict weather on Jupiter now that they have a more detailed understanding of it. The research could contribute to climate modeling, with computer simulations of the temperature cycles and how they affect weather – not just for Jupiter, but for all the giant planets in our solar system and beyond.

Magazine reference:

  1. Orton, GS, Antuñano, A., Fletcher, LN et al. Unexpected long-term variability in Jupiter’s tropospheric temperatures. Wet Astron (2022). DOI: 10.1038/s41550-022-01839-0