Jupiter's Magnetic Field & Source Location of Decameter Radiation Observed by Juno

The decametric radio emissions (DAM) originated in Jupiter's polar auroras have been observed from Earth since 1955 and from near-equator spacecraft such as Voyager. These emissions ought to originate along magnetic field lines at the local electron gyrofrequency. The Io-related DAM have received most attention since the 1980's. It is expected that the maximum frequency of these emissions is bounded by the maximum magnetic field strength near the footprint of the instantaneous Io Flux Tube (IFT). However, the lack of agreement between the frequency extent of Io-related decameter radiation and those predicted by Jovian magnetic field models has been hotly debated. Here, we present results from a detailed analysis of the peak frequencies and source location of the Io and non-Io-related DAM identified by Juno since May 2016, as well as how the newly proposed magnetic field model (JRM09) can accommodate the Io-DAM. We note with interest that the observed peak frequencies seem to be truncated at 37 MHz. The delay between the gyrofrequency predicted by JRM09 North IFT and the group of observed events is an indication of the lead angle between the IFT and the magnetic field line carrying the emissions, the altitude at which the DAM emissions are originated or a combination of both. Additionally, we investigate Io-DAM events to estimate the emission half-cone angle, altitude of emission, and resonant electron energy. For this we considered the JRM09 magnetic field model and study its major hemispherical asymmetrical geometry effect in the observation of Io-DAM.