Global Spatial Distribution of Dipolarization Fronts in the Saturn's Magnetosphere: Cassini Observations

Dipolarization front (DF), characterized by a sharp increase of the south-north component of the magnetic field, is suggested to play an important role in transferring plasmas, magnetic fluxes, and energy in the planetary magnetosphere. Using the measurements from the Cassini spacecraft between January 1, 2005 and June 15, 2011, we successfully selected 96 DF events, and obtained the global spatial distribution of DFs in the Saturn's magnetosphere. For the first time, we found that DFs are distributed not only in the nightside magnetotail but also in the dayside magnetosphere. The dayside DF events are mainly located from X = 10 R-S to X = 30 R-S (R-S is the Saturn's radius) while the nightside events have a wide range, up to X similar to-50 R-S. Moreover, the DFs are observed to be asymmetric in the south-northern hemisphere: similar to 70% of events in the northern hemisphere and similar to 30% of events in the southern hemisphere, which is likely to be due to the asymmetric orbit coverage of the Cassini in south-northern hemisphere. The occurrence of dayside DFs provides a strong evidence that the magnetic reconnection could also occur in the dayside of Saturn's magnetosphere. Thus, our results concerning the location and distribution of DFs are helpful for the study of the site of magnetic reconnection and energy transport/dissipation in Saturn's magnetosphere.

Automated summary

Through analyzing data from the Cassini spacecraft, researchers have identified and characterized dipolarization fronts (DF) in Saturn's magnetosphere. They found that DFs are not only present in the nightside magnetotail, but also in the dayside magnetosphere, with an asymmetric distribution between the northern and southern hemispheres. The presence of DFs on the dayside suggests that magnetic reconnection may occur in this region as well.