Multi‐instrument Investigation of the Location of Saturn's Magnetotail X‐Line

Smith, Andy, Jackman, C. M., Thomsen, M. F., Lamy, L. and Sergis, N. (2018) Multi‐instrument Investigation of the Location of Saturn's Magnetotail X‐Line. Journal of Geophysical Research: Space Physics, 123 (7). pp. 5494-5505. ISSN 2169-9380

JGR Space Physics - 2018 - Smith - Multi‐instrument Investigation of the Location of Saturn s Magnetotail X‐Line.pdf - Published Version

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Reconnection is a fundamentally important process in planetary magnetospheres, with both local and global effects. At Saturn, observations of the magnetotail reconnection site (or x-line) are rare, with only one in situ encounter reported to date. In this work, an extensive database of plasmoids and dipolarizations (Smith et al., 2016, was investigated from a multi-instrument perspective in order to probe the location and variability of the magnetotail x-line. Several clear intervals were identified in which the x-line location could be indirectly inferred to move on relatively short timescales. Two case studies are presented, the first of which concerns short-lived flows, suggesting the reconnection sites can be either short-lived (∼10 minutes) or extremely azimuthally limited (∼3RS/0.4 hr of local time). The second interval concerns the tailward motion of the reconnection site (or sites), inferred from the increasing electron temperature (and diminishing electron density) associated with the flows. This tailward motion occurs over ∼2.5 hr (approximately a quarter of a planetary rotation). The composition of the suprathermal plasma suggests that this could be an example of the gradual depletion of mass-loaded flux tubes (that must occur prior to lobe reconnection). These case studies are consistent with previous statistical work that suggested that the site of reconnection in the Kronian magnetotail can be highly dynamic.

Item Type: Article
Additional Information: Funding Information: Part of this work was discussed within an ISSI team on “How does the Solar Wind Influence the Giant Planet Magnetospheres?” led by M. F. Vogt and A. Masters (ID: 357). A. W. S. thanks M. K. Dougherty for access to Cassini Magnetometer data, and S. Kellock and L. Alconcel at Imperial College London for MAG data processing. Cassini MAG data processing activities are supported in the United Kingdom by STFC. A. W. S. thanks A. J. Coates and G. R. Lewis for CAPS/ELS moments processing. A. W. S. would like to thank C. S. Arridge, J. D. Nichols, D. G. Mitchell, T. D. Phan, and J. J. Reed for useful discussion. A. W. S. is funded by a SEPnet PhD studentship. C. M. J. is supported by a Science and Technology Facilities Council Ernest Rutherford FellowshipST/L004399/1. M. F. T. was supported by the NASA Cassini program through JPL contract 1243218 with Southwest Research Institute. L. L. was supported by CNES and CNRS PNP/PNST programs. The magnetic field and CAPS data shown in this analysis are available from the Planetary Data System ( The CAPS data are from volumes CO-E/J/S/SW-CAPS-3-UNCALIBRATED-V1.0 and CO-E/J/S/SW-CAPS-5-DDR-ELE-MOMENTS-V1.0 (where the non-penetrating radiation temperatures were used). RPWS data are accessible from the online service Data analysis and plotting were conducted in Python and MATLAB. Specifically, the Python libraries used were NumPy, SciPy, Matplotlib, and Pandas.
Uncontrolled Keywords: Cassini, magnetic reconnection, magnetotail, Saturn
Subjects: F300 Physics
F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Rachel Branson
Date Deposited: 07 Nov 2022 11:19
Last Modified: 07 Nov 2022 11:30

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