AKATSUKI data assimilation

Comprehensive picture of atmospheric circulation of Venus revealed by AKATSUKI data assimilation
This research is supported by JSPS Grant-in-Aid for Scientific Research (S), 19H05605 (2019.6-2024.3).

News

Background and objectives

Circulation structure of Venus atmosphere have not been understood well. In particular, structure of lower atmosphere of Venus has not been revealed because of the existence of thick cloud layer around 45-70 km altitude. The most prominent feature of the Venus atmospheric circulation is the "superrotaion (4-day circulation)", i.e., fast zonal wind whose velocity reaches about 100 m/s at the top of cloud layer. The velocity is tens of times faster than rotation speed of solid body of Venus. This superrotation is maintained by angular momentum transfer from solid body of Venus to its atmosphere, but the circulation associated with it has not been revealed and is a basic question of meteorology.

Under the situation, a Japanese spacecraft "Akatsuki" was successfully inserted into an orbit around Venus, and has been observing Venus by the use of four cameras. These four cameras probe different levels of Venus atmosphere. Before Akatsuki observation, data on Venus atmosphere were sparse, and, on the other hand, simulation models of Venus atmosphere was not established beacuse of lack of observation on circulation structure.

However, surprising similarities have been shown between clear images observed by "Akatsuki" and simulation results of a high resolution Venus general circulation model (AFES-Venus) (Figure 1). This implies that comparison between observation and model is possible. The objectives of our research is to approach mysteries of circulation structure of Venus atmosphere, i.e. superrotation, by achieving comparison between model and observation with the aid of the state of the art methods.

Figure 1

Method

We will produce a circulation field of Venus atmosphere which is consistent with observations in dynamical context. This is achieved by combining observational data by "Akatsuki" and simulation data by AFES-Venus by the use of "data assimilation" technique. This will be advanced further based on future observations desigined by "Akatsuki" observation simulation by the use of radio occultation observation, camera images, and wind vectors deduced by cloud tracking, and simulations by a model which includes cloud and radiative processes.

Figure 2

Archives

Events

2023.04.27 WTK Online Seminar (speaker: Toru Kouyama)@online

2023.03.27-28 Workshop on Venus atmosphere: observation, simulation, and data assimilation @CPS+online

2023.03.13 Special Lecture by Porf. Matsuda, "Atmospheric Waves" #4@Kyoto Sangyo U.+online

2023.01.24 Special Lecture by Porf. Matsuda, "Atmospheric Waves" #3@Kyoto Sangyo U.+online

2022.12.21 Special Lecture by Porf. Matsuda, "Atmospheric Waves" #2@Kyoto Sangyo U.+online

2022.11.16 Special Lecture by Porf. Matsuda, "Atmospheric Waves" #1@online

2022.11.08 WTK Online Seminar (speaker: Masaru Yamamoto)@online

2022.07.26 WTK Online Seminar (speaker: Hinako Onuma)@online

2022.04.28 Lecture on data assimilation (speaker: Jianyu Liang/Richard) @CPS+online

2022.03.28-29 Workshop on Venus atmosphere: observation, simulation, and data assimilation @online

2021.10.01 Special Lecture by Porf. Matsuda, "Venus Atmosphere" #7@online

2021.09.16 Special Lecture by Porf. Matsuda, "Venus Atmosphere" #6@online

2021.08.06 Special Lecture by Porf. Matsuda, "Venus Atmosphere" #5@online

2021.07.14 Special Lecture by Porf. Matsuda, "Venus Atmosphere" #4@online

2021.06.25 Special Lecture by Porf. Matsuda, "Venus Atmosphere" #3@online

2021.06.11 Special Lecture by Porf. Matsuda, "Venus Atmosphere" #2@online

2021.05.21 Special Lecture by Porf. Matsuda, "Venus Atmosphere" #1@online

2021.04.06 12th Venus atmosphere "Learning from the Past" seminar (speaker: Takeshi Imamura) @online

2021.03.18 11th Venus atmosphere "Learning from the Past" seminar (speaker: Takehiko Sato) @online

2021.03.10,11,15 Workshop on Venus atmosphere: observation, simulation, and data assimilation @online

2021.01.21 10th Venus atmosphere "Learning from the Past" seminar (speaker: George Hashimoto) @online

2021.01.12 9th Venus atmosphere "Learning from the Past" seminar (speaker: George Hashimoto) @online

2020.12.25 8th Venus atmosphere "Learning from the Past" seminar (speaker: George Hashimoto) @online

2020.12.17 7th Venus atmosphere "Learning from the Past" seminar (speaker: Masahiro Takagi) @online

2020.12.04 6th Venus atmosphere "Learning from the Past" seminar (speaker: Masahiro Takagi) @online

2020.11.25 5th Venus atmosphere "Learning from the Past" seminar (speaker: Masaru Yamamoto) @online

2020.11.16 4th Venus atmosphere "Learning from the Past" seminar (speaker: Masaru Yamamoto) @online

2020.10.14 3rd Venus atmosphere "Learning from the Past" seminar (speaker: Yoshihisa Matsuda) @online

2020.10.08 CPS/WTK Seminar "On the maintenance mechanism of the superrotation of the Venusian atmosphere: suggestion from Akatsuki" (speaker: Takeshi Horinouchi) @online

2020.10.06 CPS/WTK Seminar "Superrotation in Planetary Atmospheres" (speaker: Takeshi Imamura) @online

2020.09.23 2nd Venus atmosphere "Learning from the Past" seminar (speaker: Yoshihisa Matsuda) @online

2020.09.08 1st Venus atmosphere "Learning from the Past" seminar (speaker: Yoshihisa Matsuda) @online

2020.04.07 Online discussion for Akatsuki data assimilation @online

2020.03.20 Online meeting for Akatsuki data assimilation @online

2020.03.20-21 Workshop on atmospheric models of Venus and others @CPS => postponed

2020.01.25 3rd workshop on phenomena in Venus atmosphere @AIST Tokyo Waterfront

2019.12.23 2nd workshop on phenomena in Venus atmosphere @Hiyoshi, Keio U.

2019.12.02 1st workshop on phenomena in Venus atmosphere @Rikkyo U.

2019.08.13 Meeting on Venus data assimilation @CPS

2019.07.09 On-line seminar (Fukuya, U. Tokyo)

2019.07.01 Workshop on continous observations in winter 2018 @Hiyoshi, Keio U.

Related Links

Akatsuki DA wiki (access restricted)