Kelvin-helmholtz Instability and MHD Surface Waves on Saturn's Magnetopause

The surface waves on Saturn's magnetopause are studied by examining the Kelvin-Hel-mholtz (K-H) instability at the interface between the magnetosheath and the magnetosp-here. It is demonstrated that the relative motion between corotating magnetospheric plasma and flowing magnetosheath plasma can provide free energy to generate the K-Hinstability at the magnetopause. On the afternoon side, the closer to the subsolar point, the more unstable is the magnetopause; and the instability conditions are satisfied most easily in the morning region. Using the MHD approximation and for parameters selected to represent the Voyager-1 inbound magnetopause crossing at Saturn, the wave characteristics which are in good agreement with the corresponding estimated values of observations reported by Lep-ping et al. (1981) is obtained.