Solar wind driven thermospheric winds over the Venus North Polar region
A lateral, +Y directed, flow of Energetic Neutral Atoms (ENAs) is observed over the Venus polar region. The general similarity between the solar wind H+ (SWH+), ionospheric O+, and ENA flow pattern over the North Pole suggests that ion Charge Exchange (CE) processes produce the ENAs in the Venus thermosphere. The dusk-dawn +Y directed flow, and height distribution of ion and ENA fluxes supports the CE scenario. Moreover, the ENA dusk-dawn and noon-midnight flux asymmetry is also consistent with the asymmetric interaction, leading to higher ENA fluxes in the dayside and dawn (+Y). A model that derives the ENA flux distribution based on SWH+ and O+ fluxes in a model thermosphere is consistent with ENA flux observations. The intensity of the combined ion and ENA flow implies significant kinetic forcing of the Venus polar thermosphere, with implications such as redistribution and/or removals of neutrals.
Created 2014-02-05 12:08:39 by Mats HolmstrÃ¶m Last changed 2014-02-06 23:14:37 by Mats HolmstrÃ¶m