Gurnett, 2010 BqBq B tot Ring Current and Asymmetric Ring Current Magnetospheres of the Outer Planets - Boston, MA July 13, 2011 BRBqBfBtBRBqBfBt dB q

Regions of Interest Sergis et al, 2010 Magnetospheres of the Outer Planets - Boston, MA July 13, 2011 We divided Saturn’s equatorial ring current into 3 radial regions based on their magnetic and plasma properties.

Determining the Rotation Rate ccf=0.68 ccf=0.03 Magnetospheres of the Outer Planets - Boston, MA July 13, 2011 We chose a rotation rate and assigned the data a longitude (  ) assuming that rotation rate. A sinusoidal fit of the form A sin (  + B) + C was performed on the organized data. The rate that gave the highest correlation coefficient was chosen. w=799.2deg/day w=814 deg/day Poor fit Better fit

Introduction to Format of Results ccf=0.58 The left panel plots the correlation coefficient of each fit between 790 deg/day and 820 deg/day, taken every 0.1 degree. The shaded gray region indicates 85% of the highest peak. The horizontal line is at 50% correlation coefficient, the cutoff for inclusion. The vertical lines indicate the best fits. On the right, the data are organized by the rotation rate with the highest correlation coefficient and are plotted versus phase. The sinusoidal fit is drawn in black on top of the data, and the correlation coefficient is shown. Magnetospheres of the Outer Planets - Boston, MA July 13, 2011

6 < R < 9 9 < R < < R < Magnetic Perturbation Pressure ccf=0.58 ccf=0.68 Magnetospheres of the Outer Planets - Boston, MA July 13, 2011

ccf=0.58 ccf= < R < < R < 15 Total Ion Pressure (MIMI + CAPS) ccf= < R < 9 Magnetospheres of the Outer Planets - Boston, MA July 13, 2011

CAPS Ion Effective Temperature was only well organized in the region between 6 and 9 Saturn radii. Regions outside of 9 Rs had correlation coefficients below 0.5. CAPS Ion Effective Temperature [P/n] Magnetospheres of the Outer Planets - Boston, MA July 13, 2011 ccf=0.71

July 13, 2011 Magnetospheres of the Outer Planets - Boston, MA D A Gurnett et al. Science 2007;316: RPWS Electron Density – 3 to 5 Rs July 13, 2011 Gurnett, et al. have shown that the RPWS electron density data inside of 5 Rs tracks the SLS3 longitude. This is very close to the SLS4 South rotation rate. Outside of 5 Rs, there is no organization of the particle density in either the RPWS electron data or the CAPS Ion data. The correlation coefficient is less than 0.5.

Thermal Ion Perturbation Pressure Magnetic Perturbation Pressure ddBth (Persoon) RPWS Electron Density (Persoon) RPWS Electron Density (Gurnett) CAPS Ion Temperature Equatorial Rotation Rates Magnetospheres of the Outer Planets - Boston, MA July 13, 2011

Phase Relation Between Temperature and Pressure Magnetospheres of the Outer Planets - Boston, MA July 13, 2011 Magnetic Pressure and CAPS Ion Effective Temperature, organized at a rotation rate of 800 deg/day, are out of phase between 6 and 9 Rs. Density is not organized by the rotation rate of 800 deg/day. CAPS Ion Pressure appears to be in quadrature with the other parameters, but as the correlation coefficient with the fit is 0.38, a conclusive statement cannot be made.

Why might this be - CAM Model There is a pressure peak in the range 5 to 10 RS and the peak rotates at the SKR period. The Jia et al. model shows that inside of 5 Rs the density varies azimuthally (not illustrated), in accord with the electron density data described by Gurnett et al. data. Outside of 5 Rs, the model predicts no azimuthal dependence on density, as we have found. This implies that the azimuthal pressure variation arises through an azimuthal temperature variation. Outside of ~10 Rs, there is no temperature variation, as seen in both the data and this simulation. Jia, Kivelson, and Gombosi, Submitted, Magnetospheres of the Outer Planets - Boston, MA July 13, 2011

Why might this be - Vortex Model 13 K. K. Khurana et al. PSG 2011 D. A. Gurnett et al. Science 2007;316: P. C. Brandt et al, GRL 2010 The inflow region would act like a giant suction hose which gathers and funnels hotter plasma of the middle magnetosphere towards the inner magnetosphere. At the mouth of the inflow region (8-12 Rs), the plasma is hot and tenuous. In the outflow region, the plasma is cold and dense forming a partial ring current. The plasma in the ring current region may not be corotational but the pressure peak would be. Magnetospheres of the Outer Planets - Boston, MA July 13, 2011

d(Magnetic Pressure) Magnetospheres of the Outer Planets - Boston, MA July 13, 2011

S S N S N d(Magnetic Pressure): Change Over Time Magnetospheres of the Outer Planets - Boston, MA July 13, 2011

Conclusions  Statistically significant rotation rates in ranges near SKR frequencies that organize the plasma parameters in late 2005 through early 2006 were not found.  Some rotation rates (preferred) stood out above the background by 15%.  In this “meta-analysis” perspective, the preferred frequencies cluster near the SLS4 North and South frequencies.  Magnetic pressure oscillates in late 2005 through early 2006 at the SLS4 South and the SLS4 North frequencies.  CAPS Ion Energy and the Magnetic Perturbation Pressure are in anti-phase in the equatorial plane between 6 and 9 Rs.  The 2009 magnetic pressure does not show two distinct peaks at the north and south SLS frequencies, but shows a broadened peak over the interval containing both. Magnetospheres of the Outer Planets - Boston, MA July 13, 2011

Inertial Contribution Thermal Particle Pressure Magnetic Perturbation Pressure Curvature Force Force Balance in Equatorial Ring Current Magnetospheres of the Outer Planets - Boston, MA July 13, 2011 Radius

Magnetic Pressure Orbits are ~17-20 days long. Is big peak result of orbits? Magnetospheres of the Outer Planets - Boston, MA Ran out of steam. Will work on the rest tomorrow.