A Statistical Analysis of the Returning Flux Tubes in the Jovian Magnetosphere Based on Juno Observations

The interchange process is an important mechanism for radial transportation of plasma in the magnetospheres of the gas giants, namely Jupiter and Saturn. During this process, dense and cold flux tubes that move outwards are replaced by returning flux tubes with warm and tenuous plasma. There is an absence of systematical investigation of these returning flux tubes in the Jovian magnetosphere due to limited observations in the past. In this study, we conduct a statistical analysis of the magnetic variation and plasma properties inside the flux tubes inside 20 R_J, based on the observations from MAG and JADE onboard the Juno spacecraft during its first 45 perijove traverses. The results have illustrated that the flux tubes with increased magnetic field account for the majority of the events. There is no significant relationship between the events with increased or decreased magnetic field and magnetic latitude, and both types of events are observed mostly near the equatorial plane. Furthermore, the cross energy of returning flux tubes with decreased low-energy electron flux and increased high-energy electron flux is around several keV, depending on the type of magnetic field variation. These results provide great insight into the mass and magnetic flux transportation in the inner Jovian magnetosphere.