Locating the Source Field Lines of Jovian Decametric Radio Emissions

Decametric (DAM) radio emissions are one of main windows to reveal and understand the magnetospheric dynamics in the Jovian magnetosphere and its interaction with the moons. To properly interpret the physical processes behind DAMs, precisely locating the source field lines from which DAMs emit is important. Based on the state-of-art analytical model of Jovian magnetosphere, and combined with the properties of DAM emissions, we develop a method to locate the source field lines for any given DAM emission recorded in radio dynamic spectra by, e.g., Wind/Waves and STEREO/Waves. DAM emissions are generated by energetic electrons through cyclotron-Maser instability. For Io (the most active moon) related DAMs, the energetic electrons are sourced from Io's volcanic activities, and quickly trapped by neighboring Jovian magnetic field lines. Thus, Io-related DAM emissions could be used to test the reliability of the method. By applying the method to an Io-related DAM, we not only validate the method but also reveal some interesting processes behind the Io-DAMs.