JpGU-AGU Joint Meeting 2017

Presentation information

[EJ] Oral

P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS06] [EJ] Results of Venus science with Akatsuki in orbit for 1.5 year

Sat. May 20, 2017 9:00 AM - 10:30 AM Convention Hall B (International Conference Hall 2F)

convener:Takehiko Satoh(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Takeshi Horinouchi(Faculty of Environmental Earth Science, Hokkaido University), Masaru Yamamoto(Research Institute for Applied Mechanics, Kyushu University), Kevin McGouldrick(University of Colorado Boulder), Chairperson:Takehiko Satoh(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)

9:25 AM - 9:40 AM

[PPS06-02] Mesoscale to planetary-scale motions in the Venus atmosphere revealed by cloud tracking with Akatsuki IR and UV images

*Takeshi Horinouchi1, Shin-ya Murakami2, Takehiko Satoh2, Shigeto Watanabe3, Toru Kouyama4, Kazunori Ogohara5, Takeshi Imamura6, Masahiro Takagi7, Hiroki Kashimura8, Javier Peralta2, Sanjay S Limaye10, Takao M. Sato2, Masato Nakamura2, Manabu Yamada9 (1.Faculty of Environmental Earth Science, Hokkaido University, 2.JAXA/ISAS, 3.Hokkaido Information University, 4.AIST, 5.University of Shiga Prefecture, 6.University of Tokyo, 7.Kyoto Sangyo University, 8.Kobe University, 9.Chiba Institute of Technology, 10.University of Wisconsin, 11.Southwest Research Institute)

Keywords:Venus, Atmosphere, Jet, Mesoscale motion, Hydrodynamic instability, Superrotation

Since its orbital insertion on Dec 7, 2015, Akatsuki has been providing us with high quality images at multiple wavelengths for both the dayside and the nightside of Venus [1]. In this presentation, we present results based on cloud tracking. Owing to the high quality and a newly developed cloud tracking algorithm with novel error evaluation [2,3], we are able to conduct cloud tracking with unprecedented quality and resolution. In earlier studies, snapshots of wind distributions are shown mainly for demonstrations, but now we are able to seize it with confidence. We found sub-planetary-scale (down to mesoscale in terms of the Earth’s atmosphere) divergent and vertical motions on the dayside cloud top of Venus by using images from UVI, the ultraviolet imager of Akatsuki. The result suggests the existence of quasi-two-dimensional turbulent motion as well as mesoscale three-dimensional features. We also found a jet-like flow in the lower-cloud layer from the night-side images from IR2, an infrared imager of Akatsuki. The equatorial jet has not been reported previously, so its emergence indicates some temporal variability at this level. Further study is ongoing. For example, we have found vortical motions that are likely associated with barotropic instability.