Using gross averages of the azimuthal component of flow in Saturn's magnetosheath, we find that flows in the prenoon sector reach a maximum value of roughly half that of the postnoon side. Corotational magnetodisc plasma creates a much larger flow shear with solar wind plasma prenoon than postnoon. Maxwell stress tensor analysis shows that momentum can be transferred out of the magnetosphere along tangential field lines if a normal component to the boundary is present, i.e., field lines which pierce the magnetopause. A Kelvin‐Helmholtz unstable flow gives rise to precisely this situation, as intermittent reconnection allows the magnetic field to thread the boundary. We interpret the Kelvin‐Helmholtz instability acting along the magnetopause as a tangetial drag, facilitating two‐way transport of momentum through the boundary. We use reduced magnetosheath flows in the dawn sector as evidence of the importance of this interaction in Saturn's magnetosphere.
Geophysical Research Letters
American Geophysical Union
Grant or Award Name
NASA. Grant Number: NNX11AK80G JPL. Grant Number: 1243218
Scholarly Commons Citation
Burkholder, B., P. A. Delamere, X. Ma, M. F. Thomsen, R. J. Wilson, and F. Bagenal (2017), Local time asymmetry of Saturn’s magnetosheath flows, Geophys. Res. Lett., 44, 5877–5883, doi:10.1002/ 2017GL073031