Variability of Saturn's Magnetopause: Response to External and Internal Drivers

ACHILLEOS, N.; ARRIDGE, C. S.; BERTUCCI, C.; JACKMAN, C. M.; BURTON, M.; DOUGHERTY, M. K.; KHURANA, K. K.; RUSSELL, C. T.; SMITH, E. J.; TSURUTANI, B. T.

Congreso; AGU Spring Meeting 2006; 2006

The empirical shape model for Saturn's magnetopause, derived by Arridge et al from Cassini magnetometer data (JGR, 2006, submitted) has been applied to nine regularly sampled orbits of the spacecraft, as well as the Voyager trajectories. This has produced the most up-to-date statistical distribution of the subsolar (standoff) distance of the magnetopause surface. The orbital data used indicate that the most probable standoff distance in the Cassini era is ~26 Saturn radii, corresponding to solar wind dynamic pressure ~0.015 nPa. The absence of any significant departure from a normal distribution of standoff distances is consistent with a general 'log-normal' behaviour of solar wind pressure - and also indicates that magnetospheric mass loading and loss at Saturn are most likely to have a minor effect on the overall variability in magnetopause size. This is in clear contrast to the case of Jupiter studied by Joy et al (JGR 107, 2002) (whose method we have applied here for the case of Saturn).