09:00 〜 09:15
[PEM13-13] Atmospheric Gravity Waves and Solar Wind-induced Fluctuations in the Thermosphere and Ionosphere of Mars
キーワード：Mars, Thermosphere-Ionosphere, Gravity Wave
Gravity waves are ubiquitous features of planetary atmospheres. They act as conduits through which energy and momentum is transported between different regions, and as they dissipate they cause net impacts on the atmosphere that are important for a variety of processes from mixing of minor species to momentum balance and thermal balance. Owing to a combination of high wind speeds near the surface, large topographic changes and no planetary-scale magnetic field, these waves achieve far larger amplitudes in the Martian thermosphere than are typically observed at Earth. Thus, at Mars such waves may play an even more important role than they do at Earth. Without a strong magnetic field, observations of ions at Mars also commonly reveal features of gravity waves that frequently track those in the neutral atmosphere. However, the solar wind is also capable of producing fluctuations in the ions that may have wavelengths similar to gravity waves and can confuse such an analysis unless data from both ions and neutrals are used simultaneously. Here we identify characteristics of both atmospheric waves and solar-wind induced fluctuations seen in MAVEN observations of the Martian thermosphere. Utilizing a multi-fluid model, we demonstrate that atmospheric waves do not explain the fluctuations attributed to impacts of the solar wind. We then present the occurrence rates of these solar-wind impacts, their relationship to the solar wind itself, and spatial distribution across the planet.