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3. Radiative Effects on the Formation of the Stably Stratified Layer in the Lower Atmosphere of Venus.

Author

TAKAHASHI, Yoshiyuki O., HAYASHI, Yoshi-Yuki, HASHIMOTO, George L., KURAMOTO, Kiyoshi, ISHIWATARI, Masaki, and KASHIMURA, Hiroki

Subjects
VENUSIAN atmosphere, ATMOSPHERIC boundary layer, ABSORPTION coefficients, ATMOSPHERIC models, ALTITUDES
Abstract

The formation of the stable layer below about 2 x 106 Pa pressure level (about 20 km altitude) of the atmosphere of Venus detected by in situ observations is investigated by the use of a radiative-convective equilibrium model. We demonstrate that, assuming mixing ratio profiles of absorbers to be at the upper limits of the observed ranges for H2O and SO2 and the lower limit for CO, a stable layer forms as a radiative-convective equilibrium state, but its stability is lower than the observed one. Also, increasing the continuum absorption coefficient of CO2 and/or H2O, which are not well constrained observationally or experimentally, results in the formation of a stable layer whose stability is comparable to the observed one. These results suggest a practical method to form the stable layer in the dynamical models of the Venus atmosphere. Further, these results indicate that the important targets of future observations and laboratory measurements are to obtain more precise profiles of the mixing ratios of H2O, CO, and SO2 in the Venus atmosphere, and to determine the continuum absorption coefficients of those. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Super-rotation independent of horizontal diffusion reproduced in a Venus GCM (AFES-Venus)

Author

Sugimoto, Norihiko, Fujisawa, Yukiko, Komori, Nobumasa, Kashimura, Hiroki, Takagi, Masahiro, and Matsuda, Yoshihisa

Abstract

In the Venus atmosphere, fast zonal wind has been observed, which is called super-rotation, because it is much faster than the rotation period of the solid part of the planet. So far, Venus general circulation models (VGCMs) have been used to study the super-rotation and several studies obtained fully developed super-rotation faster than 100 m/s. It has been suggested that horizontal diffusion and resolution are important factors to generate and maintain the super-rotation in the general circulation model because waves which transport angular momentum are sensitive to them. Here, we investigated how the super-rotation depends on the magnitude of horizontal hyper diffusion using a VGCM (AFES-Venus) with medium and high resolutions (T42L60 and T159L120 where T and L denote the triangular truncation number for spherical harmonics and vertical levels, respectively). In both the runs, we found a parameter range where the structure of fully developed super-rotation is almost independent of the magnitude of horizontal diffusion. Spectral analysis shows that unrealistically strong super-rotation is developed when medium-scale disturbances are dissipated by stronger horizontal diffusion. On the other hand, artificially weak super-rotation is also realized because spurious small-scale disturbances are accumulated when the horizontal diffusion is too weak. We elucidated that the super-rotation reproduced in our VGCM is caused by resolved eddies. Moreover, we could estimate appropriate magnitude of horizontal diffusion by the spectral analysis. This study has broad implications for the planetary atmospheric science, not only in modeling but also in observational aspects., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

8. AKATSUKI returns to Venus

Author

Nakamura, Masato, Imamura, Takeshi, Ishii, Nobuaki, Abe, Takumi, Kawakatsu, Yasuhiro, Hirose, Chikako, Satoh, Takehiko, Suzuki, Makoto, Ueno, Munetaka, Yamazaki, Atsushi, Iwagami, Naomoto, Watanabe, Shigeto, Taguchi, Makoto, Fukuhara, Tetsuya, Takahashi, Yukihiro, Yamada, Manabu, Imai, Masataka, Ohtsuki, Shoko, Uemizu, Kazunori, Hashimoto, George L., Takagi, Masahiro, Matsuda, Yoshihisa, Ogohara, Kazunori, Sato, Naoki, Kasaba, Yasumasa, Kouyama, Toru, Hirata, Naru, Nakamura, Ryosuke, Yamamoto, Yukio, Horinouchi, Takeshi, Yamamoto, Masaru, Hayashi, Yoshi-Yuki, Kashimura, Hiroki, Sugiyama, Ko-ichiro, Sakanoi, Takeshi, Ando, Hiroki, Murakami, Shin-ya, Sato, Takao M., Takagi, Seiko, Nakajima, Kensuke, Peralta, Javier, Lee, Yeon Joo, Nakatsuka, Junichi, Ichikawa, Tsutomu, Inoue, Kozaburo, Toda, Tomoaki, Toyota, Hiroyuki, Tachikawa, Sumitaka, Narita, Shinichiro, Hayashiyama, Tomoko, Hasegawa, Akiko, and Kamata, Yukio

Published
2016
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9. Thermal tides reproduced in the assimilation results of horizontal winds obtained from Akatsuki UVI observations

Author

Fujisawa, Yukiko, primary, Murakami, Shin-ya, additional, Sugimoto, Norihiko, additional, Takagi, Masahiro, additional, Imamura, Takeshi, additional, Horinouchi, Takeshi, additional, Hashimoto, George L., additional, Ishiwatari, Masaki, additional, Enomoto, Takeshi, additional, Miyoshi, Takemasa, additional, Kashimura, Hiroki, additional, and Hayashi, Yoshi-Yuki, additional

Published
2022
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10. Initiation of a lightning search using the lightning and airglow camera onboard the Venus orbiter Akatsuki

Author

Takahashi, Yukihiro, Sato, Mitsuteru, Imai, Masataka, Lorenz, Ralph, Yair, Yoav, Aplin, Karen, Fischer, Georg, Nakamura, Masato, Ishii, Nobuaki, Abe, Takumi, Satoh, Takehiko, Imamura, Takeshi, Hirose, Chikako, Suzuki, Makoto, Hashimoto, George L., Hirata, Naru, Yamazaki, Atsushi, Sato, Takao M., Yamada, Manabu, Murakami, Shin-ya, Yamamoto, Yukio, Fukuhara, Tetsuya, Ogohara, Kazunori, Ando, Hiroki, Sugiyama, Ko-ichiro, Kashimura, Hiroki, and Ohtsuki, Shoko

Published
2018
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11. Ultraviolet imager on Venus orbiter Akatsuki and its initial results

Author

Yamazaki, Atsushi, Yamada, Manabu, Lee, Yeon Joo, Watanabe, Shigeto, Horinouchi, Takeshi, Murakami, Shin-ya, Kouyama, Toru, Ogohara, Kazunori, Imamura, Takeshi, Sato, Takao M., Yamamoto, Yukio, Fukuhara, Tetsuya, Ando, Hiroki, Sugiyama, Ko-ichiro, Takagi, Seiko, Kashimura, Hiroki, Ohtsuki, Shoko, Hirata, Naru, Hashimoto, George L., Suzuki, Makoto, Hirose, Chikako, Ueno, Munetaka, Satoh, Takehiko, Abe, Takumi, Ishii, Nobuaki, and Nakamura, Masato

Published
2018
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12. Overview of Akatsuki data products: definition of data levels, method and accuracy of geometric correction

Author

Ogohara, Kazunori, Takagi, Masahiro, Murakami, Shin-ya, Horinouchi, Takeshi, Yamada, Manabu, Kouyama, Toru, Hashimoto, George L., Imamura, Takeshi, Yamamoto, Yukio, Kashimura, Hiroki, Hirata, Naru, Sato, Naoki, Yamazaki, Atsushi, Satoh, Takehiko, Iwagami, Naomoto, Taguchi, Makoto, Watanabe, Shigeto, Sato, Takao M., Ohtsuki, Shoko, Fukuhara, Tetsuya, Futaguchi, Masahiko, Sakanoi, Takeshi, Kameda, Shingo, Sugiyama, Ko-ichiro, Ando, Hiroki, Lee, Yeon Joo, Nakamura, Masato, Suzuki, Makoto, Hirose, Chikako, Ishii, Nobuaki, and Abe, Takumi

Published
2017
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13. Topographical and Local Time Dependence of Large Stationary Gravity Waves Observed at the Cloud Top of Venus

Author

Takamura, M., Yamada, T., Kouyama, Toru, Imamura, Takeshi, Taguchi, Makoto, Fukuhara, Tetsuya, Sato, Takao M., Yamazaki, Atsushi, Futaguchi, Masahiko, Murakami, Shin-ya, Hashimoto, George L., Ueno, Munetaka, Iwagami, Naomoto, Takagi, Seiko, Takagi, Masahiro, Ogohara, Kazunori, Kashimura, Hiroki, Horinouchi, Takeshi, Sato, Naoki, Yamada, Manabu, Yamamoto, Yukio, Ohtsuki, Shoko, Sugiyama, Ko-ichiro, Ando, Hiroki, Satoh, Takehiko, and Nakamura, Masato

Subjects
Daytime, 010504 meteorology & atmospheric sciences, biology, Gravitational wave, Terminator (solar), Venus, Geophysics, biology.organism_classification, 01 natural sciences, Atmosphere, Standing wave, Local time, Brightness temperature, Physics::Space Physics, 0103 physical sciences, General Earth and Planetary Sciences, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, Geology, 0105 earth and related environmental sciences
Abstract

著者人数: 26名, Accepted: 2017-11-29, 資料番号: SA1170288000

Published
2017

14. Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki

Author

Tellmann, Silvia, Paetzold, Martin, Haeusler, Bernd, Oschlisniok, Janusz, Limaye, Sanjay, Choudhary, R. K., Lee, Yeon Joo, Imamura, Takeshi, Ando, Hiroki, Yamazaki, Atsushi, Sato, Takao M., Noguchi, Katsuyuki, Futaana, Yoshifumi, Murata, Yasuhiro, Takeuchi, Hiroshi, Hirose, Chikako, Ichikawa, Tsutomu, Toda, Tomoaki, Tomiki, Atsushi, Abe, Takumi, Yamamoto, Zen-ichi, Noda, Hirotomo, Iwata, Takahiro, Murakami, Shin-ya, Satoh, Takehiko, Fukuhara, Tetsuya, Ogohara, Kazunori, Sugiyama, Ko-ichiro, Kashimura, Hiroki, Ohtsuki, Shoko, Takagi, Seiko, Yamamoto, Yukio, Hirata, Naru, Hashimoto, George L., Yamada, Manabu, Suzuki, Makoto, Ishii, Nobuaki, Hayashiyama, Tomoko, and Nakamura, Masato

Subjects
010504 meteorology & atmospheric sciences, lcsh:Geodesy, Venus, 01 natural sciences, law.invention, Atmosphere, Orbiter, Altitude, law, 0103 physical sciences, Mixing ratio, Radio occultation, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Radio Science, Remote sensing, lcsh:QB275-343, biology, lcsh:QE1-996.5, lcsh:Geography. Anthropology. Recreation, Geology, biology.organism_classification, lcsh:Geology, Akatsuki, lcsh:G, Space and Planetary Science, Local time, Physics::Space Physics, Environmental science, Astrophysics::Earth and Planetary Astrophysics
Abstract

著者人数: 39名, Accepted: 2017-09-20, 資料番号: SA1170170000

Published
2017

15. Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki

Author

Peralta, Javier, Limaye, Sanjay S., McGouldrick, Kevin, Young, Eliot F., Horinouchi, Takeshi, Murakami, Shin-ya, Satoh, Takehiko, Ogohara, Kazunori, Kouyama, Toru, Imamura, Takeshi, Kashimura, Hiroki, Nakamura, Masato, Sato, Takao M., Sugiyama, Ko-ichiro, Takagi, Masahiro, Watanabe, Shigeto, Yamada, Manabu, and Yamazaki, Atsushi

Subjects
010504 meteorology & atmospheric sciences, Equator, FOS: Physical sciences, Venus, 01 natural sciences, Article, Latitude, law.invention, Atmosphere, Orbiter, Altitude, Planet, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), biology, Astronomy, biology.organism_classification, Physics - Atmospheric and Oceanic Physics, Atmospheric and Oceanic Physics (physics.ao-ph), Physics::Space Physics, Zonal flow, General Earth and Planetary Sciences, Astrophysics::Earth and Planetary Astrophysics, Geology, Astrophysics - Earth and Planetary Astrophysics
Abstract

著者人数: 18名, Accepted: 2017-07-25, 資料番号: SA1170060000

Published
2017

16. Initiation of a lightning search using the lightning and airglow camera onboard the Venus orbiter Akatsuki

Author

Lorenz, Ralph, Yair, Yoav, Aplin, Karen, Fischer, Georg, Takahashi, Yukihiro, Sato, Mitsuteru, Imai, Masataka, Nakamura, Masato, Ishii, Nobuaki, Abe, Takumi, Satoh, Takehiko, Imamura, Takeshi, Hirose, Chikako, Suzuki, Makoto, Hashimoto, George L., Hirata, Naru, Yamazaki, Atsushi, Sato, Takao M., Yamada, Manabu, Murakami, Shin-ya, Yamamoto, Yukio, Fukuhara, Tetsuya, Ogohara, Kazunori, Ando, Hiroki, Sugiyama, Ko-ichiro, Kashimura, Hiroki, and Ohtsuki, Shoko

Subjects
Lightning and airglow camera, 010504 meteorology & atmospheric sciences, lcsh:Geodesy, Venus, 01 natural sciences, Lightning, law.invention, Atmosphere of Venus, Flash (photography), Orbiter, law, 0103 physical sciences, Flash, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing, lcsh:QB275-343, biology, Full Paper, lcsh:QE1-996.5, lcsh:Geography. Anthropology. Recreation, Airglow, Geology, High voltage, biology.organism_classification, Avalanche photodiode, lcsh:Geology, Akatsuki, lcsh:G, Space and Planetary Science, Environmental science
Abstract

著者人数: 27名, Accepted: 2018-04-14, 資料番号: SA1180013000

Published
2018

17. Study of the superrotation of the Venusian atmosphere with Akatsuki

Author

Javier, Peralta, Sanjay, Limaye, Horinouchi, Takeshi, Takagi, Masahiro, Murakami, Shin-ya, Kouyama, Toru, Ogohara, Kazunori, Watanabe, Shigeto, Yamazaki, Atsushi, Yamada, Manabu, Nakajima, Kensuke, Hayashi, Yoshi-Yuki, Kashimura, Hiroki, Peralta, Javier, Limaye, Sanjay, Imamura, Takeshi, Satoh, Takehiko, and Nakamura, Masato

Abstract

第18回宇宙科学シンポジウム (2018年1月9日-10日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 18th Space Science Symposium (January 9-10, 2018. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 16名, 資料番号: SA6000118002, レポート番号: S1-002

Published
2018

18. Stationary Features at the Cloud Top of Venus Observed by Ultraviolet Imager Onboard Akatsuki

Author

Kitahara, Takehiko, primary, Imamura, Takeshi, additional, Sato, Takao M., additional, Yamazaki, Atsushi, additional, Lee, Yeon Joo, additional, Yamada, Manabu, additional, Watanabe, Shigeto, additional, Taguchi, Makoto, additional, Fukuhara, Tetsuya, additional, Kouyama, Toru, additional, Murakami, Shin‐ya, additional, Hashimoto, George L., additional, Ogohara, Kazunori, additional, Kashimura, Hiroki, additional, Horinouchi, Takeshi, additional, and Takagi, Masahiro, additional

Published
2019
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20. Topographical and Local Time Dependence of Large Stationary Gravity Waves Observed at the Cloud Top of Venus

Author

Kouyama, Toru, Imamura, Takeshi, Taguchi, Makoto, Fukuhara, Tetsuya, Sato, Takao M., Yamazaki, Atsushi, Futaguchi, Masahiko, Murakami, Shin-ya, Hashimoto, George L., Ueno, Munetaka, Iwagami, Naomoto, Takagi, Seiko, Takagi, Masahiro, Ogohara, Kazunori, Kashimura, Hiroki, Horinouchi, Takeshi, Sato, Naoki, Yamada, Manabu, Yamamoto, Yukio, Ohtsuki, Shoko, Sugiyama, Ko-ichiro, Ando, Hiroki, Takamura, M., Yamada, T., Satoh, Takehiko, Nakamura, Masato, 神山, 徹, 今村, 剛, 田口, 真, 福原, 哲哉, 佐藤, 隆雄, 山崎, 敦, 二口, 将彦, 村上, 真也, はしもと, じょーじ, 上野, 宗孝, 岩上, 直幹, 高木, 聖子, 高木, 征弘, 小郷原, 一智, 樫村, 博基, 堀之内, 武, 佐藤, 尚毅, 山田, 学, 山本, 幸生, 大月, 祥子, 杉山, 耕一朗, 安藤, 紘基, 佐藤, 毅彦, 中村, 正人, Kouyama, Toru, Imamura, Takeshi, Taguchi, Makoto, Fukuhara, Tetsuya, Sato, Takao M., Yamazaki, Atsushi, Futaguchi, Masahiko, Murakami, Shin-ya, Hashimoto, George L., Ueno, Munetaka, Iwagami, Naomoto, Takagi, Seiko, Takagi, Masahiro, Ogohara, Kazunori, Kashimura, Hiroki, Horinouchi, Takeshi, Sato, Naoki, Yamada, Manabu, Yamamoto, Yukio, Ohtsuki, Shoko, Sugiyama, Ko-ichiro, Ando, Hiroki, Takamura, M., Yamada, T., Satoh, Takehiko, Nakamura, Masato, 神山, 徹, 今村, 剛, 田口, 真, 福原, 哲哉, 佐藤, 隆雄, 山崎, 敦, 二口, 将彦, 村上, 真也, はしもと, じょーじ, 上野, 宗孝, 岩上, 直幹, 高木, 聖子, 高木, 征弘, 小郷原, 一智, 樫村, 博基, 堀之内, 武, 佐藤, 尚毅, 山田, 学, 山本, 幸生, 大月, 祥子, 杉山, 耕一朗, 安藤, 紘基, 佐藤, 毅彦, and 中村, 正人

Abstract

著者人数: 26名, Accepted: 2017-11-29

Published
2018

21. Initial products of Akatsuki 1-μm camera

Author

Iwagami, Naomoto, Sakanoi, Takeshi, Hashimoto, George L., Sawai, Kenta, Ohtsuki, Shoko, Takagi, Seiko, Uemizu, Kazunori, Ueno, Munetaka, Kameda, Shingo, Murakami, Shin-Ya, Nakamura, Masato, Ishii, Nobuaki, Abe, Takumi, Satoh, Takehiko, Imamura, Takeshi, Hirose, Chikako, Suzuki, Makoto, Hirata, Naru, Yamazaki, Atsushi, Sato, Takao M., Yamada, Manabu, Yamamoto, Yukio, Fukuhara, Tetsuya, Ogohara, Kazunori, Ando, Hiroki, Sugiyama, Ko-Ichiro, Kashimura, Hiroki, Kouyama, Toru, 岩上, 直幹, 坂野井, 健, はしもと, じょーじ, 大月, 祥子, 高木, 聖子, 上水, 和典, 上野, 宗孝, 亀田, 真吾, 村上, 真也, 中村, 正人, 石井, 信明, 阿部, 琢美, 佐藤, 毅彦, 今村, 剛, 廣瀬, 史子, 鈴木, 睦, 平田, 成, 山崎, 敦, 佐藤, 隆雄, 山田, 学, 山本, 幸生, 福原, 哲哉, 小郷原, 一智, 安藤, 紘基, 杉山, 耕一朗, 樫村, 博基, 神山, 徹, Iwagami, Naomoto, Sakanoi, Takeshi, Hashimoto, George L., Sawai, Kenta, Ohtsuki, Shoko, Takagi, Seiko, Uemizu, Kazunori, Ueno, Munetaka, Kameda, Shingo, Murakami, Shin-Ya, Nakamura, Masato, Ishii, Nobuaki, Abe, Takumi, Satoh, Takehiko, Imamura, Takeshi, Hirose, Chikako, Suzuki, Makoto, Hirata, Naru, Yamazaki, Atsushi, Sato, Takao M., Yamada, Manabu, Yamamoto, Yukio, Fukuhara, Tetsuya, Ogohara, Kazunori, Ando, Hiroki, Sugiyama, Ko-Ichiro, Kashimura, Hiroki, Kouyama, Toru, 岩上, 直幹, 坂野井, 健, はしもと, じょーじ, 大月, 祥子, 高木, 聖子, 上水, 和典, 上野, 宗孝, 亀田, 真吾, 村上, 真也, 中村, 正人, 石井, 信明, 阿部, 琢美, 佐藤, 毅彦, 今村, 剛, 廣瀬, 史子, 鈴木, 睦, 平田, 成, 山崎, 敦, 佐藤, 隆雄, 山田, 学, 山本, 幸生, 福原, 哲哉, 小郷原, 一智, 安藤, 紘基, 杉山, 耕一朗, 樫村, 博基, and 神山, 徹

Abstract

著者人数: 28名, Accepted: 2017-12-25

Published
2018

22. Absolute calibration of brightness temperature of the Venus disk observed by the Longwave Infrared Camera onboard Akatsuki

Author

Fukuhara, Tetsuya, Taguchi, Makoto, Imamura, Takeshi, Hayashitani, Akane, Yamada, Takeru, Futaguchi, Masahiko, Kouyama, Toru, Sato, Takao M., Takamura, Mao, Iwagami, Naomoto, Nakamura, Masato, Suzuki, Makoto, Ueno, Munetaka, Hashimoto, George L., Sato, Mitsuteru, Takagi, Seiko, Yamazaki, Atsushi, Yamada, Manabu, Murakami, Shin-ya, Yamamoto, Yukio, Ogohara, Kazunori, Ando, Hiroki, Sugiyama, Ko-ichiro, Kashimura, Hiroki, Ohtsuki, Shoko, Ishii, Nobuaki, Abe, Takumi, Satoh, Takehiko, Hirose, Chikako, Hirata, Naru, 福原, 哲哉, 田口, 真, 今村, 剛, 二口, 将彦, 佐藤, 隆雄, 岩上, 直幹, 中村, 正人, 鈴木, 睦, 上野, 宗孝, はしもと, じょーじ, 佐藤, 光輝, 高木, 聖子, 山崎, 敦, 山田, 学, 村上, 真也, 山本, 幸生, 小郷原, 一智, 安藤, 紘基, 杉山, 耕一朗, 樫村, 博基, 大月, 祥子, 石井, 信明, 阿部, 琢美, 佐藤, 毅彦, 廣瀬, 史子, 平田, 成, Fukuhara, Tetsuya, Taguchi, Makoto, Imamura, Takeshi, Hayashitani, Akane, Yamada, Takeru, Futaguchi, Masahiko, Kouyama, Toru, Sato, Takao M., Takamura, Mao, Iwagami, Naomoto, Nakamura, Masato, Suzuki, Makoto, Ueno, Munetaka, Hashimoto, George L., Sato, Mitsuteru, Takagi, Seiko, Yamazaki, Atsushi, Yamada, Manabu, Murakami, Shin-ya, Yamamoto, Yukio, Ogohara, Kazunori, Ando, Hiroki, Sugiyama, Ko-ichiro, Kashimura, Hiroki, Ohtsuki, Shoko, Ishii, Nobuaki, Abe, Takumi, Satoh, Takehiko, Hirose, Chikako, Hirata, Naru, 福原, 哲哉, 田口, 真, 今村, 剛, 二口, 将彦, 佐藤, 隆雄, 岩上, 直幹, 中村, 正人, 鈴木, 睦, 上野, 宗孝, はしもと, じょーじ, 佐藤, 光輝, 高木, 聖子, 山崎, 敦, 山田, 学, 村上, 真也, 山本, 幸生, 小郷原, 一智, 安藤, 紘基, 杉山, 耕一朗, 樫村, 博基, 大月, 祥子, 石井, 信明, 阿部, 琢美, 佐藤, 毅彦, 廣瀬, 史子, and 平田, 成

Abstract

著者人数: 30名, Accepted: 2017-09-29

Published
2018

23. Absolute calibration of brightness temperature of the Venus disk observed by the Longwave Infrared Camera onboard Akatsuki

Author

Hayashitani, Akane, Yamada, Takeru, Kouyama, Toru, Takamura, Mao, Fukuhara, Tetsuya, Taguchi, Makoto, Imamura, Takeshi, Futaguchi, Masahiko, Sato, Takao M., Iwagami, Naomoto, Nakamura, Masato, Suzuki, Makoto, Ueno, Munetaka, Hashimoto, George L., Sato, Mitsuteru, Takagi, Seiko, Yamazaki, Atsushi, Yamada, Manabu, Murakami, Shin-ya, Yamamoto, Yukio, Ogohara, Kazunori, Ando, Hiroki, Sugiyama, Ko-ichiro, Kashimura, Hiroki, Ohtsuki, Shoko, Ishii, Nobuaki, Abe, Takumi, Satoh, Takehiko, Hirose, Chikako, and Hirata, Naru

Subjects
Brightness, 010504 meteorology & atmospheric sciences, Infrared, lcsh:Geodesy, Venus, Baffle, 01 natural sciences, law.invention, Orbiter, Optics, law, 0103 physical sciences, Thermal infrared, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, lcsh:QB275-343, biology, business.industry, lcsh:QE1-996.5, lcsh:Geography. Anthropology. Recreation, Longwave, Geology, biology.organism_classification, lcsh:Geology, Akatsuki, lcsh:G, Space and Planetary Science, Limb darkening, Brightness temperature, business
Abstract

著者人数: 30名, Accepted: 2017-09-29, 資料番号: SA1170171000

Published
2017

24. 金星探査機「あかつき」の撮像データを用いた雲追跡による大気擾乱研究

Author

Peralta, Javier, Horinouchi, Takeshi, Murakami, Shin-ya, Kouyama, Toru, Ogohara, Kazunori, Imamura, Takeshi, Takagi, Masahiro, Kashimura, Hiroki, Yamada, Manabu, Yamazaki, Atsushi, Watanabe, Shigeto, Satoh, Takehiko, Sato, Takao, and Nakamura, Masato

Abstract

第30回大気圏シンポジウム（2016年12月5日-6日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県, 30th Atmospheric Science Symposium (December 5-6, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 14名, 資料番号: SA6000062028, レポート番号: V-5

Published
2016

25. 簡易金星版 AFES における運動エネルギースペクトル解析

Author

Kashimura, Hiroki, Sugimoto, Norihiko, Takagi, Masahiro, Matsuda, Yoshihisa, Ofuchi, Wataru, Enomoto, Takeshi, Nakajima, Kensuke, Takahashi, Yoshiyuki, and Hayashi, Yoshiyuki

Abstract

第30回大気圏シンポジウム（2016年12月5日-6日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県, 30th Atmospheric Science Symposium (December 5-6, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000062037, レポート番号: VII-3

Published
2016

27. Initial products of Akatsuki 1-μm camera

Author

Iwagami, Naomoto, primary, Sakanoi, Takeshi, additional, Hashimoto, George L., additional, Sawai, Kenta, additional, Ohtsuki, Shoko, additional, Takagi, Seiko, additional, Uemizu, Kazunori, additional, Ueno, Munetaka, additional, Kameda, Shingo, additional, Murakami, Shin-ya, additional, Nakamura, Masato, additional, Ishii, Nobuaki, additional, Abe, Takumi, additional, Satoh, Takehiko, additional, Imamura, Takeshi, additional, Hirose, Chikako, additional, Suzuki, Makoto, additional, Hirata, Naru, additional, Yamazaki, Atsushi, additional, Sato, Takao M., additional, Yamada, Manabu, additional, Yamamoto, Yukio, additional, Fukuhara, Tetsuya, additional, Ogohara, Kazunori, additional, Ando, Hiroki, additional, Sugiyama, Ko-ichiro, additional, Kashimura, Hiroki, additional, and Kouyama, Toru, additional

Published
2018
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28. Development of an ensemble Kalman filter data assimilation system for the Venusian atmosphere

Author

10358765, Sugimoto, Norihiko, Yamazaki, Akira, Kouyama, Toru, Kashimura, Hiroki, Enomoto, Takeshi, Takagi, Masahiro, 10358765, Sugimoto, Norihiko, Yamazaki, Akira, Kouyama, Toru, Kashimura, Hiroki, Enomoto, Takeshi, and Takagi, Masahiro

Abstract

The size and mass of Venus is similar to those of the Earth; however, its atmospheric dynamics are considerably different and they are poorly understood due to limited observations and computational difficulties. Here, we developed a data assimilation system based on the local ensemble transform Kalman filter (LETKF) for a Venusian Atmospheric GCM for the Earth Simulator (VAFES), to make full use of the observational data. To examine the validity of the system, two datasets were assimilated separately into the VAFES forecasts forced with solar heating that excludes the diurnal component Qz; one was created from a VAFES run forced with solar heating that includes the diurnal component Qt, whereas the other was based on observations made by the Venus Monitoring Camera (VMC) onboard the Venus Express. The VAFES-LETKF system rapidly reduced the errors between the analysis and forecasts. In addition, the VAFES-LETKF system successfully reproduced the thermal tide excited by the diurnal component of solar heating, even though the second datasets only included horizontal winds at a single altitude on the dayside with a long interval of approximately one Earth day. This advanced system could be useful in the analysis of future datasets from the Venus Climate Orbiter ‘Akatsuki’.

Published
2017

29. 金星探査機「あかつき」の撮像データを用いた雲追跡による大気擾乱研究

Author

堀之内, 武, 村上, 真也, 神山, 徹, 小郷原, 一智, 今村, 剛, 高木, 征弘, 樫村, 博基, Peralta, Javier, 山田, 学, 山崎, 敦, 渡辺, 重十, 佐藤, 毅彦, 佐藤, 隆雄, 中村, 正人, Horinouchi, Takeshi, Murakami, Shin-ya, Kouyama, Toru, Ogohara, Kazunori, Imamura, Takeshi, Takagi, Masahiro, Kashimura, Hiroki, Yamada, Manabu, Yamazaki, Atsushi, Watanabe, Shigeto, Satoh, Takehiko, Sato, Takao, Nakamura, Masato, 堀之内, 武, 村上, 真也, 神山, 徹, 小郷原, 一智, 今村, 剛, 高木, 征弘, 樫村, 博基, Peralta, Javier, 山田, 学, 山崎, 敦, 渡辺, 重十, 佐藤, 毅彦, 佐藤, 隆雄, 中村, 正人, Horinouchi, Takeshi, Murakami, Shin-ya, Kouyama, Toru, Ogohara, Kazunori, Imamura, Takeshi, Takagi, Masahiro, Kashimura, Hiroki, Yamada, Manabu, Yamazaki, Atsushi, Watanabe, Shigeto, Satoh, Takehiko, Sato, Takao, and Nakamura, Masato

Abstract

会議情報: 第30回大気圏シンポジウム（2016年12月5日-6日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県, 著者人数: 14名, Meeting Information: 30th Atmospheric Science Symposium (December 5-6, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan

Published
2017

30. Vertical structure of the axi-asymmetric temperature disturbance in the Venusian polar atmosphere: Comparison between radio occultation measurements and GCM results

Author

Ando, Hiroki, Imamura, Takeshi, Sugimoto, Norihiko, Takagi, Masahiro, Kashimura, Hiroki, Tellmann, Silvia, Paetzold, Martin, Haeusler, Bernd, Matsuda, Yoshihisa, Ando, Hiroki, Imamura, Takeshi, Sugimoto, Norihiko, Takagi, Masahiro, Kashimura, Hiroki, Tellmann, Silvia, Paetzold, Martin, Haeusler, Bernd, and Matsuda, Yoshihisa

Abstract

Vertical temperature profiles at 40-75km around 80 degrees N in the Venus polar vortex are retrieved over 13Earth days almost continuously from radio occultation measurements (Venus Express radio occultation) in the Venus Express mission. They show periodical variations with a dominant period of approximate to 3.1Earth days. These fluctuations are confined in an altitude range of 45-65km with a local minimum at approximate to 58km altitude, where the static stability abruptly increases with height. The phase of the temperature fluctuations is almost reversed at the 58km level and varies little above and below this altitude. A numerical simulation of a Venusian atmospheric general circulation model (GCM) shows that the axi-asymmetric temperature disturbance with zonal wave number 1 is predominant at 50-75km levels in the model atmosphere. The vertical structure of the reproduced disturbance agrees quite well with that retrieved by the radio occultation measurement: amplitude of the temperature fluctuation has a local minimum and its phase is reversed at the altitude (65km in the model) where the static stability rapidly changes as in the observations. Above and below this altitude, the phase is almost constant in the vertical direction. The relationship among the temperature, horizontal winds, and geopotential height associated with the simulated disturbance suggests that the axi-asymmetric temperature disturbance observed in the Venus polar region can be interpreted as neutral barotropic Rossby waves related to barotropic instability in the polar region. Plain Language Summary Vertical structure of the axi-asymmetric temperature disturbance, which has been observed by previous infrared measurements, is clarified by Venus Express radio occultation measurements. In addition, Venusian general circulation model (GCM) named Atmospheric GCM for the Earth Simulator for Venus could reproduce both horizontal and vertical structures of the disturbance, and its three-dimension

Published
2017

31. Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki

Author

Imamura, Takeshi, Ando, Hiroki, Tellmann, Silvia, Paetzold, Martin, Haeusler, Bernd, Yamazaki, Atsushi, Sato, Takao M., Noguchi, Katsuyuki, Futaana, Yoshifumi, Oschlisniok, Janusz, Limaye, Sanjay, Choudhary, R. K., Murata, Yasuhiro, Takeuchi, Hiroshi, Hirose, Chikako, Ichikawa, Tsutomu, Toda, Tomoaki, Tomiki, Atsushi, Abe, Takumi, Yamamoto, Zen-ichi, Noda, Hirotomo, Iwata, Takahiro, Murakami, Shin-ya, Satoh, Takehiko, Fukuhara, Tetsuya, Ogohara, Kazunori, Sugiyama, Ko-ichiro, Kashimura, Hiroki, Ohtsuki, Shoko, Takagi, Seiko, Yamamoto, Yukio, Hirata, Naru, Hashimoto, George L., Yamada, Manabu, Suzuki, Makoto, Ishii, Nobuaki, Hayashiyama, Tomoko, Lee, Yeon Joo, Nakamura, Masato, Imamura, Takeshi, Ando, Hiroki, Tellmann, Silvia, Paetzold, Martin, Haeusler, Bernd, Yamazaki, Atsushi, Sato, Takao M., Noguchi, Katsuyuki, Futaana, Yoshifumi, Oschlisniok, Janusz, Limaye, Sanjay, Choudhary, R. K., Murata, Yasuhiro, Takeuchi, Hiroshi, Hirose, Chikako, Ichikawa, Tsutomu, Toda, Tomoaki, Tomiki, Atsushi, Abe, Takumi, Yamamoto, Zen-ichi, Noda, Hirotomo, Iwata, Takahiro, Murakami, Shin-ya, Satoh, Takehiko, Fukuhara, Tetsuya, Ogohara, Kazunori, Sugiyama, Ko-ichiro, Kashimura, Hiroki, Ohtsuki, Shoko, Takagi, Seiko, Yamamoto, Yukio, Hirata, Naru, Hashimoto, George L., Yamada, Manabu, Suzuki, Makoto, Ishii, Nobuaki, Hayashiyama, Tomoko, Lee, Yeon Joo, and Nakamura, Masato

Abstract

After the arrival of Akatsuki spacecraft of Japan Aerospace Exploration Agency at Venus in December 2015, the radio occultation experiment, termed RS (Radio Science), obtained 19 vertical profiles of the Venusian atmosphere by April 2017. An onboard ultra-stable oscillator is used to generate stable X-band downlink signals needed for the experiment. The quantities to be retrieved are the atmospheric pressure, the temperature, the sulfuric acid vapor mixing ratio, and the electron density. Temperature profiles were successfully obtained down to similar to 38 km altitude and show distinct atmospheric structures depending on the altitude. The overall structure is close to the previous observations, suggesting a remarkable stability of the thermal structure. Local time-dependent features are seen within and above the clouds, which is located around 48-70 km altitude. The H2SO4 vapor density roughly follows the saturation curve at cloud heights, suggesting equilibrium with cloud particles. The ionospheric electron density profiles are also successfully retrieved, showing distinct local time dependence. Akatsuki RS mainly probes the low and middle latitude regions thanks to the near-equatorial orbit in contrast to the previous radio occultation experiments using polar orbiters. Studies based on combined analyses of RS and optical imaging data are ongoing.

Published
2017

32. Initial products of Akatsuki 1-μm camera

Author

Sawai, Kenta, Iwagami, Naomoto, Sakanoi, Takeshi, Hashimoto, George L., Ohtsuki, Shoko, Takagi, Seiko, Uemizu, Kazunori, Ueno, Munetaka, Kameda, Shingo, Murakami, Shin-Ya, Nakamura, Masato, Ishii, Nobuaki, Abe, Takumi, Satoh, Takehiko, Imamura, Takeshi, Hirose, Chikako, Suzuki, Makoto, Hirata, Naru, Yamazaki, Atsushi, Sato, Takao M., Yamada, Manabu, Yamamoto, Yukio, Fukuhara, Tetsuya, Ogohara, Kazunori, Ando, Hiroki, Sugiyama, Ko-Ichiro, Kashimura, Hiroki, and Kouyama, Toru

Subjects
010504 meteorology & atmospheric sciences, lcsh:Geodesy, Venus, Radiation, Nightside surface, 01 natural sciences, Planet, 0103 physical sciences, Mixing ratio, 010303 astronomy & astrophysics, Image resolution, 0105 earth and related environmental sciences, Remote sensing, lcsh:QB275-343, biology, lcsh:QE1-996.5, Detector, lcsh:Geography. Anthropology. Recreation, Geology, biology.organism_classification, Dayside cloud, lcsh:Geology, Wavelength, lcsh:G, Space and Planetary Science, Infrared, Orbit insertion
Abstract

著者人数: 28名, Accepted: 2017-12-25, 資料番号: SA1170201000

Published
2018

33. Overview of Akatsuki data products: definition of data levels, method and accuracy of geometric correction

Author

Lee, Yeon Joo, Ogohara, Kazunori, Takagi, Masahiro, Murakami, Shin-ya, Horinouchi, Takeshi, Yamada, Manabu, Kouyama, Toru, Hashimoto, George L., Imamura, Takeshi, Yamamoto, Yukio, Kashimura, Hiroki, Hirata, Naru, Sato, Naoki, Yamazaki, Atsushi, Satoh, Takehiko, Iwagami, Naomoto, Taguchi, Makoto, Watanabe, Shigeto, Sato, Takao M., Ohtsuki, Shoko, Fukuhara, Tetsuya, Futaguchi, Masahiko, Sakanoi, Takeshi, Kameda, Shingo, Sugiyama, Ko-ichiro, Ando, Hiroki, Nakamura, Masato, Suzuki, Makoto, Hirose, Chikako, Ishii, Nobuaki, and Abe, Takumi

Subjects
Brightness, 010504 meteorology & atmospheric sciences, Coordinate system, lcsh:Geodesy, Venus, Ellipse-ftting technique, Ellipse-fitting technique, Ellipse, 01 natural sciences, law.invention, Orbiter, law, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing, Data processing, lcsh:QB275-343, biology, lcsh:QE1-996.5, lcsh:Geography. Anthropology. Recreation, Geology, biology.organism_classification, Data product, lcsh:Geology, lcsh:G, Space and Planetary Science, Brightness temperature, Radiance, Pointing correction
Abstract

著者人数: 31名, Accepted: 2017-11-27, 資料番号: SA1170173000

Published
2017

34. Performance of Akatsuki/IR2 in Venus orbit: the first year

Author

Satoh, Takehiko, primary, Sato, Takao M., additional, Nakamura, Masato, additional, Kasaba, Yasumasa, additional, Ueno, Munetaka, additional, Suzuki, Makoto, additional, Hashimoto, George L., additional, Horinouchi, Takeshi, additional, Imamura, Takeshi, additional, Yamazaki, Atsushi, additional, Enomoto, Takayuki, additional, Sakurai, Yuri, additional, Takami, Kosuke, additional, Sawai, Kenta, additional, Nakakushi, Takashi, additional, Abe, Takumi, additional, Ishii, Nobuaki, additional, Hirose, Chikako, additional, Hirata, Naru, additional, Yamada, Manabu, additional, Murakami, Shin-ya, additional, Yamamoto, Yukio, additional, Fukuhara, Tetsuya, additional, Ogohara, Kazunori, additional, Ando, Hiroki, additional, Sugiyama, Ko-ichiro, additional, Kashimura, Hiroki, additional, and Ohtsuki, Shoko, additional

Published
2017
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35. Absolute calibration of brightness temperature of the Venus disk observed by the Longwave Infrared Camera onboard Akatsuki

Author

Fukuhara, Tetsuya, primary, Taguchi, Makoto, additional, Imamura, Takeshi, additional, Hayashitani, Akane, additional, Yamada, Takeru, additional, Futaguchi, Masahiko, additional, Kouyama, Toru, additional, Sato, Takao M., additional, Takamura, Mao, additional, Iwagami, Naomoto, additional, Nakamura, Masato, additional, Suzuki, Makoto, additional, Ueno, Munetaka, additional, Hashimoto, George L., additional, Sato, Mitsuteru, additional, Takagi, Seiko, additional, Yamazaki, Atsushi, additional, Yamada, Manabu, additional, Murakami, Shin-ya, additional, Yamamoto, Yukio, additional, Ogohara, Kazunori, additional, Ando, Hiroki, additional, Sugiyama, Ko-ichiro, additional, Kashimura, Hiroki, additional, Ohtsuki, Shoko, additional, Ishii, Nobuaki, additional, Abe, Takumi, additional, Satoh, Takehiko, additional, Hirose, Chikako, additional, and Hirata, Naru, additional

Published
2017
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36. Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki

Author

Imamura, Takeshi, primary, Ando, Hiroki, additional, Tellmann, Silvia, additional, Pätzold, Martin, additional, Häusler, Bernd, additional, Yamazaki, Atsushi, additional, Sato, Takao M., additional, Noguchi, Katsuyuki, additional, Futaana, Yoshifumi, additional, Oschlisniok, Janusz, additional, Limaye, Sanjay, additional, Choudhary, R. K., additional, Murata, Yasuhiro, additional, Takeuchi, Hiroshi, additional, Hirose, Chikako, additional, Ichikawa, Tsutomu, additional, Toda, Tomoaki, additional, Tomiki, Atsushi, additional, Abe, Takumi, additional, Yamamoto, Zen-ichi, additional, Noda, Hirotomo, additional, Iwata, Takahiro, additional, Murakami, Shin-ya, additional, Satoh, Takehiko, additional, Fukuhara, Tetsuya, additional, Ogohara, Kazunori, additional, Sugiyama, Ko-ichiro, additional, Kashimura, Hiroki, additional, Ohtsuki, Shoko, additional, Takagi, Seiko, additional, Yamamoto, Yukio, additional, Hirata, Naru, additional, Hashimoto, George L., additional, Yamada, Manabu, additional, Suzuki, Makoto, additional, Ishii, Nobuaki, additional, Hayashiyama, Tomoko, additional, Lee, Yeon Joo, additional, and Nakamura, Masato, additional

Published
2017
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37. Erratum: Corrigendum: Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki

Author

Horinouchi, Takeshi, primary, Murakami, Shin-ya, additional, Satoh, Takehiko, additional, Peralta, Javier, additional, Ogohara, Kazunori, additional, Kouyama, Toru, additional, Imamura, Takeshi, additional, Kashimura, Hiroki, additional, Limaye, Sanjay S., additional, McGouldrick, Kevin, additional, Nakamura, Masato, additional, Sato, Takao M., additional, Sugiyama, Ko-ichiro, additional, Takagi, Masahiro, additional, Watanabe, Shigeto, additional, Yamada, Manabu, additional, Yamazaki, Atsushi, additional, and Young, Eliot F., additional

Published
2017
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38. Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki

Author

Horinouchi, Takeshi, primary, Murakami, Shin-ya, additional, Satoh, Takehiko, additional, Peralta, Javier, additional, Ogohara, Kazunori, additional, Kouyama, Toru, additional, Imamura, Takeshi, additional, Kashimura, Hiroki, additional, Limaye, Sanjay S., additional, McGouldrick, Kevin, additional, Nakamura, Masato, additional, Sato, Takao M., additional, Sugiyama, Ko-ichiro, additional, Takagi, Masahiro, additional, Watanabe, Shigeto, additional, Yamada, Manabu, additional, Yamazaki, Atsushi, additional, and Young, Eliot F., additional

Published
2017
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42. 大気大循環モデルを用いた金星極域の構造に関する理論的研究

Author

Ando, Hiroki, Sugimoto, Norihiko, Takagi, Masahiro, Kashimura, Hiroki, and Imamura, Takeshi

Abstract

第28回大気圏シンポジウム（2014年12月8日-9日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県, 28th Atmospheric Science Symposium (December 8-9, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000069016, レポート番号: Ⅱ-10

Published
2014

43. Performance of Akatsuki/IR2 in Venus orbit: the first year

Author

Sakurai, Yuri, Sawai, Kenta, Satoh, Takehiko, Sato, Takao M., Nakamura, Masato, Kasaba, Yasumasa, Ueno, Munetaka, Suzuki, Makoto, Hashimoto, George L., Horinouchi, Takeshi, Imamura, Takeshi, Yamazaki, Atsushi, Enomoto, Takayuki, Takami, Kosuke, Nakakushi, Takashi, Abe, Takumi, Ishii, Nobuaki, Hirose, Chikako, Hirata, Naru, Yamada, Manabu, Murakami, Shin-ya, Yamamoto, Yukio, Fukuhara, Tetsuya, Ogohara, Kazunori, Ando, Hiroki, Sugiyama, Ko-ichiro, Kashimura, Hiroki, and Ohtsuki, Shoko

Subjects
Elliptic orbit, 010504 meteorology & atmospheric sciences, lcsh:Geodesy, Venus, Cryo-cooler, 01 natural sciences, Window, Optics, Near-infrared, Orbiter, 0103 physical sciences, Calibration, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing, Aerosols, lcsh:QB275-343, biology, business.industry, Atmosphere, Detector, lcsh:QE1-996.5, lcsh:Geography. Anthropology. Recreation, Geology, Astrometry, biology.organism_classification, Dynamics, lcsh:Geology, Orbit, Akatsuki, lcsh:G, Space and Planetary Science, Deconvolution, business, Noise (radio)
Abstract

著者人数: 28名, Accepted: 2017-10-23, 資料番号: SA1170148000

Published
2017

48. Regime Diagrams of Solutions in an Idealized Quasi-Axisymmetric Model for Superrotation of Planetary Atmospheres

Author

30167027, KASHIMURA, Hiroki, YODEN, Shigeo, 30167027, KASHIMURA, Hiroki, and YODEN, Shigeo

Abstract

This paper presents regime diagrams illustrating the parametric dependence of dynamical balance in a superrotating atmosphere produced in a quasi-axisymmetric idealized system with strong horizontal diffusion studied previously by the present authors. In this system, the superrotation is maintained by the Gierasch mechanism, which possibly explains the four-day circulation in the atmosphere of Venus. Our previous paper developed a theoretical model of this system to estimate the superrotation strength and showed that the parametric dependence of the superrotation strength can be consolidated into three non-dimensional external parameters. The present study analyzes the theoretical model to determine boundaries of the regimes based on the dynamical balance and plots theoretical regime diagrams, which are important to understand the non-linear dynamical system and are useful to clearly describe the parametric dependence. Further, a parametric limit of the theoretical model is also estimated and included in the diagrams. The parametric limit shows both a lower limit for the horizontal diffusion and an upper limit of the superrotation strength in the Gierasch mechanism. The regime diagram demonstrates that the superrotation in the cyclostrophic balance is realized when the horizontal Ekman number is in a certain range whose width is mainly controlled by the vertical Ekman number. Numerical solutions covering a vast region in the parameter space are obtained by time-integrations of the primitive equations, and the dynamical regimes in the numerical solutions are compared with the theoretical regime diagrams. The theoretical regime diagrams agree well with the numerical results in most regions, confirming the validity of the theoretical model. Multiple equilibrium solutions are obtained when the horizontal Ekman number is lower than the theoretical limit. Moreover, they show that the Gierasch mechanism can maintain the superrotation even with the horizontal diffusion weak

Published
2015

49. Ultraviolet imager on Venus orbiter Akatsukiand its initial results

Author

Yamazaki, Atsushi, Yamada, Manabu, Lee, Yeon, Watanabe, Shigeto, Horinouchi, Takeshi, Murakami, Shin-ya, Kouyama, Toru, Ogohara, Kazunori, Imamura, Takeshi, Sato, Takao, Yamamoto, Yukio, Fukuhara, Tetsuya, Ando, Hiroki, Sugiyama, Ko-ichiro, Takagi, Seiko, Kashimura, Hiroki, Ohtsuki, Shoko, Hirata, Naru, Hashimoto, George, Suzuki, Makoto, Hirose, Chikako, Ueno, Munetaka, Satoh, Takehiko, Abe, Takumi, Ishii, Nobuaki, and Nakamura, Masato

Abstract

The ultraviolet imager (UVI) has been developed for the Akatsukispacecraft (Venus Climate Orbiter mission). The UVI takes ultraviolet (UV) images of the solar radiation reflected by the Venusian clouds with narrow bandpass filters centered at the 283 and 365 nm wavelengths. There are absorption bands of SO2and unknown absorbers in these wavelength regions. The UV images provide the spatial distribution of SO2and the unknown absorber around cloud top altitudes. The images also allow us to understand the cloud top morphologies and haze properties. Nominal sequential images with 2-h intervals are used to understand the dynamics of the Venusian atmosphere by estimating the wind vectors at the cloud top altitude, as well as the mass transportation of UV absorbers. The UVI is equipped with off-axial catadioptric optics, two bandpass filters, a diffuser installed in a filter wheel moving with a step motor, and a high sensitivity charge-coupled device with UV coating. The UVI images have spatial resolutions ranging from 200 m to 86 km at sub-spacecraft points. The UVI has been kept in good condition during the extended interplanetary cruise by carefully designed operations that have maintained its temperature maintenance and avoided solar radiation damage. The images have signal-to-noise ratios of over 100 after onboard desmear processing.

Published
2018
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50. Protein stabilization utilizing a redefined codon

Author

Ohtake, Kazumasa, primary, Yamaguchi, Atsushi, additional, Mukai, Takahito, additional, Kashimura, Hiroki, additional, Hirano, Nobutaka, additional, Haruki, Mitsuru, additional, Kohashi, Sosuke, additional, Yamagishi, Kenji, additional, Murayama, Kazutaka, additional, Tomabechi, Yuri, additional, Itagaki, Takashi, additional, Akasaka, Ryogo, additional, Kawazoe, Masahito, additional, Takemoto, Chie, additional, Shirouzu, Mikako, additional, Yokoyama, Shigeyuki, additional, and Sakamoto, Kensaku, additional

Published
2015
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