11:45 AM - 12:00 PM
[PEM12-10] Identifying atmospheric waves and solar wind impacts in the Martian thermosphere and ionosphere
Keywords:Mars, atmospheric wave, solar wind, thermosphere, ionosphere
We found a great agreement with atmospheric gravity waves for the neutral-neutral coupling at the low altitudes (170-190 km). This agreement decreases at higher altitudes (190-210 km). The ion perturbations follow the neutral perturbations – a sign of ion-neutral coupling, which can be almost explained by the atmospheric gravity waves but not as good as the neutral-neutral coupling. The ion-neutral coupling gets lower at higher altitudes. This feature can be found in both day and night side. For the extreme solar wind events with coronal mass ejections, we got essentially the same result in the neutral coupling as we had in the quiet cases. The big difference is the abrupt drop in the ion-neutral coupling. That is consistent with a strong disruption related to solar wind electric field on ions. The ions move independent of the neutrals, do not reflect the atmospheric gravity waves. Ion-specific features are significant especially in the nightside and at higher altitudes. In at least some cases, the transition is consistent with the increasing gyro/collision frequency ratio. It is noteworthy that a small fraction of the neutral-neutral coupling could be explained by the acoustic waves, and none of the ion-neutral coupling by the acoustic waves.