UC Berkeley study finds ammonia plumes changing Jupiter’s atmosphere

Diagram of moist convection on Jupiter
Helen Xu/Staff

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Ammonia plumes on Jupiter have affected the planet’s atmosphere and are changing the colors of its bands, according to a recent study by UC Berkeley researchers.

Lead author of the study and UC Berkeley professor of astronomy and earth and planetary science Imke de Pater and her colleagues, including campus graduate student Chris Moeckel, published a study Wednesday that focused on ammonia plumes and proposed a mechanism by which the plumes were generated in Jupiter’s atmosphere.

The research team conducted an observation campaign in conjunction with NASA’s Juno space probe that currently orbits Jupiter. The data gathered in December 2016 and January 2017 documented a storm outbreak of ammonia plumes, according to Moeckel.

These ammonia plumes are located 80 kilometers above the water-cloud layer in Jupiter’s atmosphere and occur cyclically every five to seven years, according to Moeckel.

“We see that this sort of event happens on a regular basis,” Moeckel said. “We assume that if it happens on a regular basis that there is a certain mechanism that happens that makes it occur constantly.”

The mechanism the study proposes is that water clouds act as a lid for the lower atmosphere. As pressure builds up over several years, materials such as ammonia break through the layer and form plumes.

“As the pressure against this lid starts building up … every five to seven years there’s so much energy stored that the lid, the water clouds, is not strong enough to hold it anymore,” Moeckel said.

Afterward, water immediately condenses out of the ammonia that rises above the water-cloud layer in a process called “moist convection.” As water condenses, latent heat is released and gives the ammonia energy to rise 80 kilometers above the water clouds and form ammonia plumes, according to Moeckel.

For reference, the highest plumes generated by volcanic eruptions on Earth are around 30 to 40 kilometers high, according to Moeckel.

“We’re trying to understand what are the mechanisms that transport materials in the atmosphere, and plumes are a very important mechanism to essentially mix up your atmosphere,” Moeckel said.

The rise of these plumes causes color changes in Jupiter’s atmosphere. The plumes bring more ammonia to the upper parts of the atmosphere and creates white ammonia clouds, whereas lower-level clouds are generally brown.

The research team will continue its observational campaign and hopes to uncover more about Jupiter’s atmosphere going forward, according to Moeckel.

“The more data we get, the more we can understand how little we understand,” Moeckel said. “We’re moving away from the picture of Jupiter as a planet that quietly orbits the sun and going towards one where Jupiter is constantly subjected to massive storms.”

Aishwarya Kaimal is the lead research and ideas reporter. Contact her at [email protected] and follow her on Twitter at @Aishwarya_R_K‏.