The narrowband kilometric radiation (nKOM) is a Jovian low-frequency radio component identified as a plasma emission produced in the region of the Io plasma torus. Measurements from the Waves instrument onboard the Juno spacecraft permitted to establish the distribution of nKOM occurrence and intensity versus frequency and latitude.

We have developed a new 3D geometrical model called LsPRESSO (Large scale Plasma Radio Emission Simulation of Spacecraft Observations), that can simulate at large scale, the plasma emissions occurrence observed by a spacecraft. With this model, we propose a new method to discriminate the generation mechanism, propagation mode, frequency, beaming and radio source location of plasma emissions. Here, this method is applied for the study of the nKOM observed by the Juno/Waves spacecraft to identify which conditions best reproduce the observed occurrence distribution versus frequency and latitude. 

This study modeling is based on the VIP4 internal Jovian magnetic field model and a diffusive equilibrium model of the plasma density in Jupiter's inner magnetosphere. Our method applied to LsPRESSO allows us to exclude the two main nKOM models published so far, and to show that the emission must be produced at the local plasma frequency and beamed along the local gradient of these frequencies in the direction of decreasing frequencies. We also prove that depending on its latitude, Juno observes two distinct kinds of nKOM: a low frequency nKOM in ordinary mode at high latitudes and a high frequency nKOM in extraordinary mode at low latitudes. Both radio source locations are found to be distributed near the centrifugal equator from the outer edge to the inner edge of the Io plasma torus.