Friction layer along the sides of the plasma channels in the Venus nightside ionosphere

Magnus force in the Venus ionosphere

“…It is thus possible to argue that the solar wind that has eroded the upper ionosphere behind the magnetic polar regions is also subject to the dawnward directed response to the Magnus force that is applied to the rotating plasma; that is, the plasma channels will also be bent in the dawnward direction as they extend downstream from the magnetic polar regions. A similar argument can also be invoked to account for the dawnward displacement from the midnight plane where most of the density plateau profiles are observed in the nightside [ Pérez‐de‐Tejada , 2005]. Even though the dawnward displacement of these latter features is less pronounced than that of the ionospheric holes both phenomena exhibit a displacement that is similar to that of the transterminator flow.…”

“…An important property of these latter features is that the region where they mostly occur is located in the near dawn vicinity of the midnight plane (the center of that region is located ∼1 hour LST away from that plane) and thus implies an east‐west asymmetry of the plasma configuration in the nightside [ Brace et al , 1982]. A similar consideration can also be made from the region where the electron density plateau profiles are observed [ Pérez‐de‐Tejada , 2005]. Even though these latter profiles mostly occur near the midnight plane the region where they are seen also exhibits a dawn ward displacement but not as pronounced as that of the ionospheric holes.…”

Solar wind‐driven plasma fluxes from the Venus ionosphere

“…Pressure gradient forces are not sufficient to drive the supersonic transterminator ionospheric flow where the solar wind is instead expected to carve out plasma channels from the polar regions over the nightside hemisphere. The latter provides an interpretation of ionospheric holes and serves to account for the extended nightside ionosphere that is observed by the midnight plane [ Pérez‐de‐Tejada , , ]. A condition required to support dynamic processes as the source of the plasma channels is that the kinetic energy density of the plasma by the polar regions (kinetic pressure) is larger than the local magnetic energy density (magnetic pressure) and that in this sense the solar wind is responsible for driving the plasma clouds.…”

Fluid Dynamics in Space Sciences

“…Calculations of a momentum conservation equation applied to this problem led to such result which is unrelated to pressure gradient forces across the terminator that have also been suggested to account for the Venus ionospheric flow 9 . The (supersonic) speed of the ionospheric flow and its asymmetry in latitude which is indicated by differences in the extent of the region where the ionospheric plasma is displaced downstream from Venus argues more favorably in terms of momentum transport which mostly occurs by the magnetic polar regions of the Venus ionosphere 11 . It should be noted in this regard that the ¨magnetic polar regions¨ are related to the position where the solar magnetic field fluxes that are convected by the solar wind, and that first pile up around the dayside ionosphere to form a magnetic barrier 12 , slip over the planet to take the shape of a hairpin at those regions and then enter the wake 13 .…”