Plasma flows in Saturn's nightside magnetosphere

• Published in: Journal of geophysical research. Space physics 2014-06, Vol.119 (6), p.4521-4535
• Main Authors: Thomsen, M. F., Jackman, C. M., Tokar, R. L., Wilson, R. J.
• Format: Article
• Language: English
• Subjects: Astrophysics; Cassini mission; Corotation; Field of view; Ionosphere; Magnetic fields; Magnetic properties; Magnetopause; Magnetosphere; Mass spectrometry; Numerical integration; Outflow; Planetary magnetic fields; Planetary magnetospheres; Plasma; plasma flow; Saturn; Saturn magnetotail
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1002/2014JA019912

The plasma properties, especially the flow parameters, obtained from numerical integration of Cassini Plasma Spectrometer (CAPS) Ion Mass Spectrometer measurements during intervals when the CAPS field of view encompassed both inward and outward flow directions relative to corotation are examined for nightside data (18–06 local time) during 2006, 2009, and 2010. The results show good agreement with previously reported values derived using different selection criteria and a different analysis technique. Nightside flows are predominantly in or near the corotation direction, indicating continuing influence of connection to the ionosphere. There is no evidence for a quasi‐steady reconnection x line within the surveyed region of the tail, although dynamic events attributable to transient reconnection have been observed. There is a net radial mass outflow, leading to an estimated net mass loss between 18 and 03 local time of ~34 kg/s. Part of this mass loss occurs as a “planetary wind” along the dusk flank. The remainder probably occurs ultimately much deeper in the tail and along the distant dawn magnetopause, when the mass disconnects from the weakened planetary magnetic field. Key Points Plasma properties in Saturn's magnetotail are reported Nightside flows are predominantly in or near the corotation direction Net radial mass outflow with estimated nightside mass loss of ~34 kg/s