Saturn's magnetospheric refresh rate
Article first published online: 4 JUN 2013
©2013. American Geophysical Union. All Rights Reserved.
Geophysical Research Letters
Volume 40, Issue 11, pages 2479–2483, 16 June 2013
How to Cite
2013), Saturn's magnetospheric refresh rate, Geophys. Res. Lett., 40, 2479–2483, doi:10.1002/grl.50530., , , , , and (
- Issue published online: 3 JUL 2013
- Article first published online: 4 JUN 2013
- Accepted manuscript online: 3 MAY 2013 06:44PM EST
- Manuscript Revised: 2 MAY 2013
- Manuscript Accepted: 2 MAY 2013
- Manuscript Received: 29 MAR 2013
 A 2–3 day periodicity observed in Jupiter's magnetosphere (superposed on the giant planet's 9.5 h rotation rate) has been associated with a characteristic mass-loading/unloading period at Jupiter. We follow a method derived by Kronberg et al. () and find, consistent with their results, that this period is most likely to fall between 1.5 and 3.9 days. Assuming the same process operates at Saturn, we argue, based on equivalent scales at the two planets, that its period should be 4 to 6 times faster at Saturn and therefore display a period of 8 to 18 h. Applying the method of Kronberg et al. for the mass-loading source rates estimated by Smith et al. () based on data from the third and fifth Cassini-Enceladus encounters, we estimate that the expected magnetospheric refresh rate varies from 8 to 31 h, a range that includes Saturn's rotation rate of ~10.8 h. The magnetospheric period we describe is proportional to the total mass-loading rate in the system. The period is, therefore, faster (1) for increased outgassing from Enceladus, (2) near Saturn solstice (when the highest proportion of the rings is illuminated), and (3) near solar maximum when ionization by solar photons maximizes. We do not claim to explain the few percent jitter in period derived from Saturn Kilometric Radiation with this model, nor do we address the observed difference in period observed in the north and south hemispheres.