Chance observations in 1955 logged strong radio frequency oscillations from Jupiter between the Kilometric (1000s metres) and Decametric (10s metres) wavebands. NASA's Juno spacecraft scanned Jupiter in late 2016 and made recordings of the emissions. See: New images of Jupiter offer glimpse into what lies under planet's skin The Guardian, 03 Sep. 2016.
The driving mechanism(s) behind the emissions are not yet understood :
“These emissions are the strongest in the solar system. Now we are going to try to figure out where the electrons come from that are generating them.”
Further info and history: Decametric Radiation from Jupiter
Also see: Jupiter - atmospheric heating