Global Spatial Distribution of Dipolarization Fronts in the Saturn's Magnetosphere: Cassini Observations. Issue 17 (4th September 2021)

• Record Type: Journal Article
• Authors: Xu, S. B.; Huang, S. Y.; Yuan, Z. G.; Deng, X. H.; Jiang, K.; Wei, Y. Y.; Zhang, J.; Zhang, Z. H.; Xiong, Q. Y.; Yu, L.; Lin, R. T.; Waite, J. H.
• Is Part Of: Geophysical research letters. Volume 48:Issue 17(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-09-04
• Subjects: dipolarization fronts -- Saturn's magnetosphere -- global spatial distribution -- magnetic reconnection; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL092701
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: 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 ∼−50 R S . Moreover, the DFs are observed to be asymmetric in the south‐northern hemisphere: ∼70% of events in the northern hemisphere and ∼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. Plain Language Summary: Saturn's magnetosphere is influenced by not only the solar wind, but more importantly the internal sources. Therefore, its magnetosphere would show different characteristics from terrestrial planets. Dipolarization front (DF), characterized by a sharp increase of the south‐north component of the magnetic field, is directly and closely related to magnetic reconnection, planetary substorm and planetary aurora, and can be a great medium for studying the magnetosphere's response to the solar wind and internal sources. In this work, using the measurements from the Cassini, we selected 96 DF events and obtained the global spatial distribution of DFs in the Saturn's magnetosphere. For the first time, we found that quite a big portion of DF events appear in the dayside magnetosphere. Therefore, we propose that the dynamics processes that generally occur at the magnetotail can extend to the whole magnetosphere in Saturn. Our work provides further evidence for the previous studies that the magnetic reconnection occurs in Saturn's dayside magnetodisc. Key Points: A complete global distribution is provided to show the location and local time of dipolarization fronts in Saturn's magnetosphere There is a surprising large portion of dipolarization fronts observed at the dayside of Saturn's magnetosphere Our results support the existence of dayside magnetodisc reconnection in Saturn