Jupiter's banded appearance is caused by a "weather layer" formed by clouds. This composite image shows infrared and visible (left-to-right) views of Jupiter taken by the Gemini Northern Telescope and NASA's Hubble Space Telescope, respectively.
影像来源：International Gemini Observatory/NOIRLab/NSF/AURA/NASA/ESA, M.H. Wong and I. de Pater (UC Berkeley) et al.
The new discovery of NASA's Juno probe orbiting Jupiter provides a more complete picture of the planet's unique and colorful atmospheric features, providing clues to the unknown processes beneath its clouds. These results highlight the internal work of the cloud belts and cloud belts around Jupiter, as well as its polar cyclones and even the Great Red Spot.
The researchers today published several papers on Juno's atmospheric discovery in Science and the Journal of Geophysical Research: Planets. Other papers have been published in two recent issues of Geophysical Research Letters.
"These new observations from Juno open up a new reservoir of information for Jupiter's mysterious observable features." Lori Glaze, director of nasa's planetary science division at its Washington headquarters, said. "Each paper sheds light on a different aspect of Earth's atmospheric processes – a perfect example of how our international diverse team of scientists is strengthening their understanding of the solar system."
Image credit: JunoCam; Image data: NASA/JPL-Caltech/SwRI/MSSS; JunoCam image processing: Kevin M. Gill (CC BY); Earth image: NASA
This illustration combines images of Jupiter taken by Juno camera instruments aboard NASA's Juno spacecraft and a composite image of Earth to depict the size and depth of Jupiter's Great Red Spot.
Juno entered jupiter's orbit in 2016. Each of the spacecraft's 37 passes through Jupiter to date has had a dedicated set of instruments beneath its turbulent clouds.
"Previously, Juno gave us a surprise by suggesting that the phenomena in Jupiter's atmosphere were deeper than expected," said Scott Bolton, principal investigator of juno at the Southwestern Institute in San Antonio and lead author of a paper in science on the depth of Jupiter's vortexes. "Now, we're starting to put all these individual pieces together and for the first time in 3D to really understand how Jupiter's beautiful and violent atmosphere works."
Juno's microwave radiometer (MWR) allows scientists to glimpse what's going on beneath 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 deep red vortex, wider than Earth, has piqued the interest of scientists since it was discovered about two centuries ago.
The new results show that the top temperature of the cyclone is higher and the atmosphere density is lower, while the bottom temperature is lower and the density is higher. An anticyclone that rotates in the opposite direction is the opposite – the top temperature is lower and the bottom temperature is higher.
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, stretched more than 200 miles (350 km). This surprising finding suggests that the area covered by the vortex extends 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 means that instruments studying Jupiter's gravitational field may be able to detect the concentration of atmospheric mass in storms. Juno's two close-range over Jupiter's most famous sites provided an opportunity to search for gravitational signatures of the storm and complemented the depth results of the MWR.
As Juno flew low over Jupiter's clouds at about 130,000 mph (209,000 km/h), Juno scientists used NASA's deep-space network tracking antenna to measure 0.01 millimeters per second at a distance of more than 400 million miles (650 million kilometers). This allowed the research team to limit the depth of the Great Red Spot to about 300 miles (500 kilometers) below the cloud tops.
"The precision Juno needed to acquire the gravity of the Great Red Spot during its july 2019 flight to the Great Red Spot was staggering," said Marzia Parisi, a Juno scientist at NASA's Jet Propulsion Laboratory in Southern California and lead author of a paper in Science on the Gravitational Overflight of the Great Red Spot. "Being able to complement MWR's discoveries in depth gives us great confidence that future gravity experiments on Jupiter will yield equally interesting results."
Cloud belts and cloud zones
In addition to cyclones and anticyclones, Jupiter is also known for its unique bands of white and red clouds that surround Jupiter. Strong east-west winds in opposite directions separated these cloud bands. 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 was moving in a significant straight line with the observed jet stream.
"By tracking ammonia, we found circulations in the northern and southern hemispheres that are similar in nature to the Ferrer circulation, which controls most of the earth's climate." Karen Durr said he is a graduate student at the Weizmann Institute of Science in Israel and the lead author of a paper in the Journal of Science on Jupiter's Ferrer circulation. "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 these cloud belts and cloud areas shifted about 40 miles (65 kilometers) below Jupiter's water clouds. At shallower depths, Jupiter's cloud bands are brighter in microwave light than in neighboring regions. But deeper beneath the water clouds, the opposite is true – revealing similarities with our oceans.
"We call this layer 'Jovicline,' similar to the transition layer in Earth's oceans called the thermoclinic – the seawater shifts sharply from relatively warm to relatively cold." Leigh Fletcher said he was a juno participating scientist at the University of Leicester in the United Kingdom and lead author of the paper in the Journal of Geophysical Research: Planets Highlight Juno's Microwave Observations of Jupiter's Temperate Zones and Regions.
Polar cyclones
Juno previously found polygonal arrangements for giant cyclonic storms at the poles of Jupiter —eight in octagonals to the north and five to 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 have extremely strong elasticity to stay in the same position.
"Jupiter's cyclones affect each other's motion, causing them to sway around an equilibrium position," said Alessandro Mura, a co-investigator on juno at the National Institute of Astrophysics in Rome. He recently published a paper in Geophysical Research Letters that focused on the oscillations and stability of Jupiter's polar cyclones. "These slowly rocking behaviors show 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 balance explains the location of cyclones and the different number of hurricanes at each pole.
More information about tasks
JPL, a division of the California Institute of Technology in Pasadena, California, manages juno missions. Juno is part of NASA's New Frontier Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama, for the agency's Science Mission Agency in Washington. Denver's Lockheed Martin Space Company built and operates the spacecraft.
JPL is a division of the California Institute of Technology in Pasadena, California, responsible for managing the Juno mission. Juno is part of NASA's New Frontier Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama, for the Washington-based Science Missions Council. Lockheed Martin Space, based in Denver, builds and operates the spacecraft.