Saturday, November 27

This is the first 3D view of Jupiter’s atmosphere

The new data from the Juno probe NASA orbiting Jupiter provides a more complete picture of its atmosphere, offering clues to the invisible processes that occur under its clouds. The results highlight the inner workings of the belts and cloud areas that surround Jupiter, as well as its polar cyclones and its well-known Great Red Spot.

An international group of researchers publishes this week several articles on these discoveries in the journals Science and the Journal of Geophysical Research: Planets, which are added to others that have recently appeared in Geophysical Research Letters, and they have also explained them in a presentation on line. “Each article sheds light on different aspects of the planet’s atmospheric processes,” he points out. Lori Glaze, director of NASA’s Division of Planetary Sciences.

Juno entered the orbit of Jupiter in 2016. During each of the 37 passes As the spacecraft has performed over the planet to date, its instruments have looked beneath its turbulent cloud cover.

“Juno has previously surprised us with indications that the phenomena in Jupiter’s atmosphere were deeper than expected,” he explains. Scott Bolton, principal investigator of this mission who works at the Southwest Research Institute in San Antonio (USA) and principal author of an article in Science over the depth of Jupiter’s vortices. “Now, we are starting to put all these individual pieces together and get our first real understanding of how Jupiter’s beautiful and violent atmosphere works in 3D.”

The radiómetro de microondas (MWR) Juno has allowed his team to peer below the tops of Jupiter’s clouds and probe the structure of its many vortex storms. The most famous is the iconic anticyclone known as Great Red Spot, a colossal storm 16,000 kilometers wide. Wider than Earth, this crimson vortex has intrigued scientists since its discovery nearly two centuries ago.

Illustration representing the size and depth of Jupiter’s Great Red Spot. NASA

The new results show that cyclones they are warmer in the upper part, with lower atmospheric densities, while they are cooler in the lower part, with higher densities. However, the anticyclones, which rotate in the opposite direction, are cooler at the top and warmest at the bottom.

The findings also indicate that these storms are much higher or deeper than expected, with some extending 100 kilometers below the cloud tops and others, including the Great Red Spot, extending more than 350 kilometers. This surprising discovery shows that vortices cover regions beyond those where water condenses and clouds form, below the depth at which sunlight warms the atmosphere.

The storms are much deeper than expected, with some extending 100 kilometers below the cloud tops and others, including the Great Red Spot, extending more than 350 kilometers.

The height and size of the Great Red Spot mean that the concentration of atmospheric mass within the storm can be detected by instruments that study Jupiter’s gravitational field. Two close flybys over it offered an opportunity to search for the gravitational signature of the storm and complement the results of the MWR on its depth.

With Juno traveling low above Jupiter’s cloud cover at around 209,000 km / h, the scientists were able to measure velocity changes as small as 0.01 millimeters per second using an antenna tracking the NASA Deep Space Network on Earth, from a distance of more than 650 million kilometers. This allowed the team limit the depth of the Great Red Spot to about 500 kilometers below the top of the clouds.

“The precision required to obtain the gravity of the Great Red Spot during the July 2019 flyby is astonishing,” he highlights. Marzia Parisi, a Juno scientist at NASA’s Jet Propulsion Laboratory in Southern California and lead author of another article in Science. “To be able to complement the finding of MWR with information on the depth; we are confident that future gravitational experiments on Jupiter will yield equally intriguing results. ”

Belts and zones

In addition to cyclones and anticyclones, Jupiter is known for its characteristic belts and zones: white and reddish bands of clouds that envelop the planet. Strong east-west winds moving in opposite directions separate the bands. Juno had previously discovered that these winds, or jet streams, reach depths of approximately 3,200 kilometers. Researchers are still trying to solve the mystery of how these currents form. The data collected by the MWR offers a possible clue: Ammonia gas in the atmosphere drifts up and down fairly in line with the observed jet streams.

The planet’s jet streams reach depths of 3,200 km and ammonia gas in the atmosphere travels up and down fairly aligned with them.

“By following ammonia, we find circulating cells in both the northern and southern hemispheres that are similar in nature to the so-called Ferrel cells, which control much of our climate here on Earth,” he says. Keren Duer, a researcher at the Weizmann Institute of Sciences in Israel and lead author of another article in Geophysical Research Letters on these structures. “While Earth has one Ferrel cell per hemisphere, Jupiter has eight, each at least 30 times larger.”

The MWR radiometer data also shows that the belts and zones transition about 65 kilometers below Jupiter’s water clouds. At shallow depths, the planet’s belts are brighter in microwave light than neighboring areas. But at deeper levels, below water clouds, the opposite occurs, revealing a similarity to our oceans.

“We call this level joviclina by analogy with the transition layer observed in the Earth’s oceans, known as thermocline, where sea water abruptly goes from being relatively warm to relatively cold ”, he explains Leigh Fletcher, a scientist at the University of Leicester (UK) and lead author of the article in the Journal of Geophysical Research: Planets where Juno’s microwave observations of Jupiter’s belts and temperate zones stand out.

Stable polar cyclones

Juno had also observed polygonal arrangements of giant cyclonic storms at both of Jupiter’s poles: eight arranged in an octagonal pattern in the north and five in a pentagonal pattern in the south. Now, five years later, the data from the Jovian Infrared Auroral Mapper (JIRAM) of the ship to determine that these atmospheric phenomena are extremely resistant, staying in the same location.

The eight cyclones of the north pole and the five of the south are extremely resistant, remaining in the same location

“Jupiter’s cyclones affect each other in their movement, causing them to oscillate around an equilibrium position,” he says. Alessandro Mura, Juno’s co-investigator at the National Institute of Astrophysics in Rome and lead author of another paper by Geophysical Research Letters on the oscillations and stability of Jupiter’s polar cyclones. “The behavior of these slow oscillations suggests that they have deep roots,” he adds.

The JIRAM data also indicates that, like hurricanes on Earth, these cyclones try to move poleward, but are pushed back by centrally located cyclones. This equilibrium explains where cyclones reside and the different numbers that appear at each pole.

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