Xin LiuMOP The growth of plasma convection in Saturn’s inner magnetosphere X. Liu; T. W. Hill; R. A. Wolf; Y. Chen Physics & Astronomy Department, Rice University, Houston, TX

Xin LiuMOP Outline Rice Convection Model (RCM) 3 plasma source models Simulation results comparison with observations

Xin LiuMOP Magnetosphere Ionosphere Coupling The Rice Convection Model (RCM) Described by Liu et al. [JGR, doi: /2010JA015859]

Xin LiuMOP Saturn’s inner magnetosphere: 2<L<12 Modeling region: 2<L<40 (Boundary condition: L=2: ; L=40: ) Ionospheric conductance:  P = constant,  H = 0 Inner plasma source models: J06 = [Johnson et al., Ap. J., 2006] S10 E3 = [Smith et al., JGR, 2010, doi: /2009JA ], “E3” version. CJ10 = [Cassidy & Johnson, Icarus, 2010, doi: /j.icarus ] RCM setup

Xin LiuMOP S10 E3 150 kg/s CJ kg/s J06 24 kg/s Comparison of 3 source models Mass loading rate Locations of charge-exchange /ionization cross-over, and of ionization peak.

Xin LiuMOP Comparison of 3 source models (Ionization rate only) S10 E3 150 kg/s CJ kg/s J06 24 kg/s

Xin LiuMOP Simulation results of J06 model

Xin LiuMOP Convection pattern at quasi steady state Slow, wide and dense outflow channels alternating with fast, narrow and tenuous inflow channels.

Xin LiuMOP Mass flux of J06 model

Xin LiuMOP Inflow longitudinal width ratio of J06 model [Observation data from Yi et al., JGR, 2010]

Xin LiuMOP Inflow and outflow channel velocities of J06 model [Observation data from Yi et al., JGR, 2010]

Xin LiuMOP Recall the mass loading rates of 3 source models J06 = 24 kg/s S10 E3 = 150 kg/s CJ10 = 160 kg/s What about scaling J06 model up to 150 kg/s mass loading rate? (Also scaling up  P with the same ratio to confine the radial velocities)

Xin LiuMOP Model: J06 Global ionization: 24 kg/s Pedersen conductance: 0.3 S Model: J06*150/24 Global ionization: 150 kg/s Pedersen conductance: 0.3*150/24 S Mass flux Outflow velocity Inflow velocity Inflow width ratio Scale up

Xin LiuMOP Model: S10 E3 Global ionization: 150 kg/s Pedersen conductance: 0.3*150/24 S Mass fluxOutflow velocityInflow velocityInflow width ratio

Xin LiuMOP Model: CJ10 Global ionization: 160 kg/s Pedersen conductance: 0.3*160/24 S Mass fluxOutflow velocityInflow velocityInflow width ratio

Xin LiuMOP Conclusions The radial distribution of plasma source plays a key role in plasma convection pattern. The higher plasma mass loading rate can be compensated by higher ionospheric Pedersen conductance. Simulations with more recent plasma source models are different from simulation with Johnson’s 06 model, and in disagreement with CAPS observations in some aspects.

Xin LiuMOP Thank you

Xin LiuMOP Supporting material

Xin LiuMOP Observed result of corotation lag Simulated result of corotation lag Corotation lag of J06 model

Xin LiuMOP Longitudinal width and radial velocity Faraday’s law for steady state: and w is the longitudinal width

Xin LiuMOP Test particles tracking of J06 model