The new discovery of NASA's Juno probe orbiting Jupiter provides a more complete picture of how the planet's unique and colorful atmospheric features provide clues to its untold processes beneath its clouds. These results highlight the inner workings of the cloud belts and regions surrounding Jupiter, Jupiter's polar cyclones, and the Great Red Spot.
The researchers published several papers thursday in the journal Science and The Journal Geophysical Research: Planets on juno's atmosphere. Other papers have appeared in two recent issues of the Geophysical Research Newsletter.
Lori Glaze, director of NASA's Department of Planetary Sciences, said: "These new observations by Juno open up a new reservoir of information for Jupiter's mysterious observable features. Each paper reveals a different aspect of the planet's atmospheric processes — a perfect example of how our internationally diverse scientific team can strengthen our understanding of our solar system. ”
Juno entered jupiter's orbit in 2016. So far, during the spacecraft's 37 overflights of the planet, a specialized set of instruments has observed beneath its turbulent clouds.
"Previously, Juno surprised us by suggesting that the phenomenon in Jupiter's atmosphere was deeper than expected," said Scott Bolton, chief investigator of Juno from the Southwest Research Institute and lead author of Science's paper on the depth of Jupiter's vortex. "Now, we're starting to put all these separate pieces together and for the first time really understand how Jupiter's beautiful and violent atmosphere works — in a 3D way."
Juno's microwave radiometer (MWR) allowed mission scientists to peek under Jupiter's cloud top and probe the structure of its many eddy storms. The most famous of these storms is the iconic anticyclone known as the Great Red Spot. This crimson storm, larger in diameter than Earth, has been attracting scientists since it was discovered nearly two centuries ago.
The new results show that cyclones are warmer at the top and have a lower atmospheric density, while at the bottom they are colder and denser. The anticyclone, which rotates in the opposite direction, is colder at the top but warmer at the bottom.
The findings also suggest that these storms were much higher than expected, with some extending 60 miles (100 km) below the cloud tops, while others, including the Great Red Spot, extended more than 200 miles (350 km). This surprising finding suggests that the vortex covers an area beyond the area of water condensation and cloud formation, below the depths of the sunlight's warm atmosphere.
The height and size of the Great Red Spot mean that the concentration of atmospheric mass in storms could be detected by instruments studying Jupiter's gravitational field. Juno made two close-range overs at Jupiter's most famous place, providing the opportunity to search for the gravitational signature of the storm and complementing mwr's results about its depth.
With Juno flying low above Jupiter's clouds at about 130,000 mph (209,000 km/h), Juno's scientists were able to use NASA's deep space network tracking antenna to measure 0.01 millimeters per second of velocity changes at distances of more than 400 million miles (650 million kilometers). This allowed the team to limit the depth of the Great Red Spot to about 300 miles (500 kilometers) below the cloud tops.
Marzia Parisi, a Juno scientist at NASA's Jet Propulsion Laboratory and lead author of a paper in science magazine on the Great Red Spot Gravity Overflight, said: "The precision required to obtain the gravity of the Great Red Spot during the July 2019 flyby is staggering. Being able to complement MWR's discovery in depth gives us great confidence that future gravity experiments on Jupiter will yield equally intriguing results. ”
Cloud belts and cloud zones
In addition to cyclones and anticyclones, Jupiter is also known for its unique cloud belts and cloud areas – white and red bands of clouds that surround Jupiter. Strong east-westerly winds moving in opposite directions separate these straps. Juno previously found that these winds, or jets, were about 2,000 miles (about 3,200 kilometers) deep. Researchers are still trying to unravel the mystery of how jet streams are formed. Data collected by Juno's MWR over multiple passes revealed a possible clue: Ammonia in the atmosphere moved up and down in apparent agreement with the observed jets.
Keren Duer, a graduate student at the Weizmann Institute of Science in Israel and lead author of a paper in the journal Science on Jupiter that resembles Ferrer cells, said: "By tracking ammonia, we have found circulations of nature similar to ferrel cells in both the northern and southern hemispheres, which control most of our climate on Earth. Each of the Earth's hemispheres has one Ferrer circulation, while Jupiter has eight—each at least 30 times larger. ”
Juno's mwr data also shows that about 40 miles (65 kilometers) below Jupiter's water clouds, the cloud belt and cloud area have undergone a transition. In shallow layers, Jupiter's bands are brighter in microwave light than in neighboring regions. But at a deeper level, beneath the water clouds, the opposite is true – and this reveals similarities with our oceans.
Leigh Fletcher, a juno participating scientist at the University of Leicester in the United Kingdom and the lead author of the paper in the journal Geophysical Research, said: "We call this layer 'jovicline' to an analogous to a transitional layer in The Earth's ocean, the so-called warm line – the sharp transition of seawater from relatively warm to relatively cold. ”
Polar whirlwind
Juno had previously spotted a giant cyclone storm with polygonal arrangements at jupiter's poles—eight octagonal arrangements in the north and five pentagons in the south. Now, five years later, mission scientists have used observations from the spacecraft's Jupiter Infrared Aurora Imager (JIRAM) to determine that these atmospheric phenomena are extremely elastic and remain in the same position.
Alessandro Mura, a juno co-researcher at the National Institute of Astrophysics in Rome and lead author of a paper on the oscillation and stability of Jupiter's polar cyclones, recently published in Geophysical Research Letters, said: "Jupiter's cyclones interact with each other to move, causing them to oscillate around an equilibrium position. These slow oscillations suggest that they have deep roots. ”
Jiram's data also suggests that, like hurricanes on Earth, these cyclones want to move toward the poles, but cyclones located at the center of each pole push them back. This equilibrium explains the position of the cyclone and the different number of poles at each pole.