Asymmetrically Distributed Kelvin‐Helmholtz Instability at Venusian Magnetosphere

Abstract The asymmetric distribution of Kelvin‐Helmholtz (KH) instability at Venusian ionopause is investigated using a multifluid model. Results show that KH instability distributes asymmetrically, preferentially developing in the −E (anti‐parallel to the interplanetary electric field) hemisphere. In the magnetosheath, solar wind H + ions deflect toward both ±E hemispheres. Within the ionosphere, however, ionospheric ions are accelerated in the +E direction by the convective electric field. In addition, the ionopause is elevated in the −E hemisphere. These effects lead to a stronger velocity shear at the ionopause of the −E hemispheric, thereby promoting the KH growth there. The magnetic field variations in the KH region correlate with the H + density but anti‐correlate with ionospheric ion density. The period of KH instability gradually decreases as it propagates downstream. During its evolution, plasma clouds form and take away ionospheric (especially O + ) ions effectively, resulting in considerable ion escape.