Smith, Andy, Jackman, C. M. and Thomsen, M. F. (2016) Magnetic reconnection in Saturn's magnetotail: A comprehensive magnetic field survey. Journal of Geophysical Research: Space Physics, 121 (4). pp. 2984-3005. ISSN 2169-9380
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JGR Space Physics - 2016 - Smith - Magnetic reconnection in Saturn s magnetotail A comprehensive magnetic field survey.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (2MB) | Preview |
Abstract
Reconnection within planetary magnetotails is responsible for locally energizing particles and changing the magnetic topology. Its role in terms of global magnetospheric dynamics can involve changing the mass and flux content of the magnetosphere. We have identified reconnection related events in spacecraft magnetometer data recorded during Cassini's exploration of Saturn's magnetotail. The events are identified from deflections in the north-south component of the magnetic field, significant above a background level. Data were selected to provide full tail coverage, encompassing the dawn and dusk flanks as well as the deepest midnight orbits. Overall 2094 reconnection related events were identified, with an average rate of 5.0 events per day. The majority of events occur in clusters (within 3 h of other events). We examine changes in this rate in terms of local time and latitude coverage, taking seasonal effects into account. The observed reconnection rate peaks postmidnight with more infrequent but steady loss seen on the dusk flank. We estimate the mass loss from the event catalog and find it to be insufficient to balance the input from the moon Enceladus. Several reasons for this discrepancy are discussed. The reconnection X line location appears to be highly variable, though a statistical separation between events tailward and planetward of the X line is observed at a radial distance of between 20 and 30RS downtail. The small sample size at dawn prevents comprehensive statistical comparison with the dusk flank observations in terms of flux closure.
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| Additional Information: | Funding Information: 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. acknowledges the Royal Astronomical Society for the support to attend the Magnetospheres of the Outer Planets 2015 conference, at which this work was presented. A.W.S. is funded by a SEPnet PhD studentship. A.W.S. thanks N. M. Pilkington for providing a list of magnetopause crossing times. CMJ is supported by a Science and Technology Ernest Rutherford Fellowship number ST/L004399/1. The magnetic field and CAPS data shown in this analysis are available from the Planetary Data System (http://pds.nasa.gov/). Work at PSI was supported by the NASA Cassini program through JPL contract 1243218 with Southwest Research Institute. The Cassini project is managed by the Jet Propulsion Laboratory for NASA. A.W.S. would like to thank J. J. Reed, J. C. Coxon, and J. A. Reidy for helpful discussions. |
| Uncontrolled Keywords: | Cassini, 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 10:40 |
| Last Modified: | 07 Nov 2022 10:45 |
| URI: | https://nrl.northumbria.ac.uk/id/eprint/50553 |
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