[P-CG19] 惑星大気圏・電磁圏

[PCG19-02] Strong contrast between aphelion and perihelion water vertical distributions on Mars as revealed by ExoMars/NOMAD

*青木 翔平^1,2、Vandaele AnnCarine²、Daerden Frank²、Villanueva Geronimo³、Liuzzi Giuliano³、Clancy R. Todd⁴、Lopez-Valverde Miguel Angel⁵、Brines Adrian⁵、Thomas Ian²、Trompet Loic²、Erwin Justin²、Neary Lori²、Robert Severine²、Piccialli Arianna²、Holmes James⁶、Patel Manish⁶、Yoshida Nao⁷、Whiteway James⁸、Smith Michael³、Ristic Bojan²、Bellucci Giancarlo⁹、Lopez-Moreno José Juan⁵ (1.宇宙航空研究開発機構 宇宙科学研究所 、2.Royal Belgian Institute for Space Aeronomy、3.NASA Goddard Space Flight Center、4.Space Science Institute、5.Instituto de Astrofísica de Andalucía、6.School of Physical Sciences, The Open University、7.東北大学、8.Centre for Research in Earth and Space Science, York University、9.Istituto di Astrofisica e Planetologia Spaziali, IAPS-INAF)

キーワード：火星、大気、水、リモーセンシング

Water cycle on Mars has been understood by the observations of water vapor abundances integrated over the whole column of atmosphere, whereas the knowledge of their altitude distributions is still limited. This study provides its new details based on daily observations of the water vapor vertical distribution collected for 3.5 years. We present a strong contrast of water vapor vertical distributions between northern and southern summer when water vapor is sublimated from the summer polar ice. We find that sublimated water vapor is confined into lower atmosphere in the northern summer, whereas it directly reaches the upper atmosphere in the southern summer. During the solstice periods, the water vertical distributions are drived by global meridional transport from summer to winter hemisphere. This study present that the transport of water vapor by the global circulation is limited by the formation of water ice clouds in the northern summer. In contrast, water is more effectively transported to the upper atmosphere and winter hemisphere in the southern summer because its vertical extent is less constrained by cloud formation due to warmer atmospheric temperature. We show that southern summer is the primary season for the supply of water vapor to the upper atmosphere, in addition to the period of strong dust storms. In the northern summer season, water transport from north to south still occurs below 10-20 km however it is much reduced relative to the southern summer season.