Using the upgraded Karl G. Jansky Very Large Array (VLA) telescope in New Mexico, astronomers have created a new radio map of Jupiter that is the most detailed yet. The map reveals the movement of large amounts of ammonia gas underneath the color bands and clouds visible on the planet with the naked eye.
The team of University of California (UC), Berkeley scientists used the VLA telescope to measure radio emissions from Jupiter's atmosphere in wavelength bands with transparent clouds, shedding light on the unexplored regions of the planet's atmosphere where cloud formation occurs.
Using the absorption of ammonia gas by the planet's thermal radio emissions, the team was able to paint a picture of the depth and amount of ammonia in the planet's atmosphere, which could help astronomers better understand its global circulation and cloud formation.
"We in essence created a three-dimensional picture of ammonia gas in Jupiter's atmosphere, which reveals upward and downward motions within the turbulent atmosphere," said Imke de Pater of UC Berkeley and lead author of the study, adding that the map resembles visible-light images that were taken using the Hubble Space Telescope.
The radio map reveals the gases that rise into and form the upper cloud layers of Jupiter's atmosphere. These gases are rich in ammonia, and the clouds that they form can be seen from Earth with optical telescopes.
In addition, the map shows the ammonia-poor air sinking in the planet in the same way that dry air makes its way downward from Earth's higher clouds.
"We now see high ammonia levels like those detected by Galileo from over 100 kilometers deep, where the pressure is about eight times Earth's atmospheric pressure, all the way up to the cloud condensation levels," de Pater said.
The radio map comes just before NASA's Juno spacecraft - set to orbit Jupiter on July 4, 2016 - will take water measurements in the planet's deep atmosphere.
"Maps like ours can help put their data into the bigger picture of what's happening in Jupiter's atmosphere," de Pater added.
The new findings also resolve the discrepancy between the ammonia concentration detected by the Galileo probe back in 1995 and the VLA telescope measurements obtained prior to 2004.
"Jupiter's rotation once every 10 hours usually blurs radio maps, because these maps take many hours to observe," said Robert Sault of the University of Melbourne and co-author of the study. "But we have developed a technique to prevent this and so avoid confusing together the upwelling and downwelling ammonia flows, which had led to the earlier underestimate."
The findings were published in the June 3 issue of the journal Science.
