Saturn's open‐closed field line boundary:a Cassini electron survey at Saturn's magnetosphere

Jasinski, Jamie M. and Arridge, Chris and Bader, Alexander and Smith, Andrew and Felici, Marianna and Kinrade, Joe and Coates, A.J. and Jones, Geraint and Nordheim, T. and Gilbert, Lin and Azari, Abigail and Badman, Sarah and Provan, G. and Sergis, N. and Murphy, Neil (2019) Saturn's open‐closed field line boundary:a Cassini electron survey at Saturn's magnetosphere. Journal of Geophysical Research: Space Physics, 124 (12). pp. 10018-10035. ISSN 2169-9402

[img]
Text (jasinski_saturns_2019)
jasinski_saturns_2019.pdf - Accepted Version
Available under License Creative Commons Attribution.

Download (2MB)

Abstract

We investigate the average configuration and structure of Saturn's magnetosphere in the nightside equatorial and high‐latitude regions. Electron data from the Cassini Plasma Spectrometer's Electron Spectrometer (CAPS‐ELS) is processed to produce a signal‐to‐noise ratio for the entire CAPS‐ELS time of operation at Saturn's magnetosphere. We investigate where the signal‐to‐noise ratio falls below 1, to identify regions in the magnetosphere where there is a significant depletion in the electron content. In the nightside equatorial region we use this to find that the most planetward reconnection x‐line location is at 20 – 25 RS downtail from the planet in the midnight to dawn sector. We also find an equatorial dawn‐dusk asymmetry at a radial distance of >20 RS which may indicate the presence of plasma depleted flux tubes returning to the dayside after reconnection in the tail. Furthermore, we find that the high‐latitude magnetosphere is predominantly in a state of constant plasma depletion and located on open field lines. We map the region of high‐latitude magnetosphere that is depleted of electrons to the polar cap to estimate the size and open flux content within the polar caps. The mean open flux content for the northern and southern polar caps are found to be 25±5 and 32±5 GWb, respectively. The average location of the open‐closed field boundary is found at invariant colatitudes of 12.7±0.6° and 14.5±0.6°. The northern boundary is modulated by planetary period oscillations more than the southern boundary.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Geophysical Research: Space Physics
Additional Information:
This is the peer reviewed version of the following article: Jasinski, J. M., Arridge, C. S., Bader, A., Smith, A. W., Felici, M., Kinrade, J., et al. ( 2019). Saturn's open‐closed field line boundary: A Cassini electron survey at Saturn's magnetosphere. Journal of Geophysical Research: Space Physics, 124, 10018– 10035. doi: 10.1111/jpim.12206 which has been published in final form at https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JA027090 This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
ID Code:
138822
Deposited By:
Deposited On:
08 Nov 2019 09:50
Refereed?:
Yes
Published?:
Published
Last Modified:
22 Sep 2020 04:49