[P-CG24] [EJ] Planetary Magnetosphere, Ionosphere, and Atmosphere

[PCG24-P05] DSMC simulations of internal gravity waves propagating and dissipating in the Martian upper thermosphere and exosphere

Kaori Terada¹, *Naoki Terada¹, Alexander S. Medvedev², Erdal Yigit³, Hiromu Nakagawa¹, Kanako Seki⁴, Takeshi Kuroda^1,5, Hiroyuki Shinagawa⁶, Hitoshi Fujiwara⁷, Yasumasa Kasaba¹ (1.Graduate School of Science, Tohoku University, 2.Max Planck Institute for Solar System Research, 3.Department of Physics and Astronomy, George Mason University, 4.Graduate School of Science, University of Tokyo, 5.Big Data Analytics Laboratory, Big Data Integration Research Center, National Institute of Information and Communications Technology, 6.National Institute of Information and Communications Technology , 7.Faculty of Science and Technology, Seikei University)

Keywords:Gravity waves, Upper thermosphere, Mars

The effects of internal gravity wave propagation and dissipation in the Martian upper thermosphere and exosphere on the density, circulation, and temperature of the background atmosphere have been studied using a multi-species Direct Simulation Monte Carlo (DSMC) model of Terada et al. (2016). This paper shows results of local simulations of a vertically propagating gravity wave mode in the Martian dayside upper thermosphere and exosphere under the conditions of the observation period of the Mars Atmosphere and Volatile EvolutioN (MAVEN) satellite. The results reveal that gravity waves which produce wave-like density perturbations around the exobase observed by Neutral Gas Ion Mass Spectrometer (NGIMS) instrument onboard the MAVEN satellite [e.g. Yigit et al., 2015; Terada et al., 2017] must have a vertical wavelength of at least 200 km, if they are propagated from the lower and middle atmosphere. We also find that a gravity wave harmonic with a 200 km vertical wavelength significantly heats and accelerates the upper thermosphere and the exosphere, increasing the mixing ratio of CO₂ above 150 km. The calculated horizontal acceleration rate is ~1200 m/s/sol, and the calculated heating rate is ~100 K/sol. The calculated rate of increase in CO₂ mixing ratio is ~80 %/sol around the ionopause, which can probably cause an increase in the escape flux ratios of CO₂⁺/O⁺ and O₂⁺/O⁺.

References
Terada et al. (2016), JGR, doi:10.1002/2015JE004961.
Terada et al. (2017), JGR, doi:10.1002/2016JA023476.
Yigit et al. (2015), GRL, doi:10.1002/2015GL065307.