Study of gravity waves in planetary atmospheres using radio occultation experiments and numerical modeling

• Project/Area Number: 16H04060
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Space and upper atmospheric physics
• Research Institution: The University of Tokyo
• Principal Investigator: Imamura Takeshi 東京大学, 大学院新領域創成科学研究科, 教授 (40311170)
• Co-Investigator(Kenkyū-buntansha): 安藤 紘基 京都産業大学, 理学部, 助教 (00706335) ; 中島 健介 九州大学, 理学研究院, 助教 (10192668) ; 林 祥介 神戸大学, 理学研究科, 教授 (20180979) ; 野口 克行 奈良女子大学, 自然科学系, 助教 (20397839) ; 杉山 耕一朗 松江工業高等専門学校, 情報工学科, 准教授 (60463733) ; 小高 正嗣 北海道大学, 理学研究院, 助教 (60344462)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥14,560,000 (Direct Cost: ¥11,200,000、Indirect Cost: ¥3,360,000); Fiscal Year 2018: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000); Fiscal Year 2017: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000); Fiscal Year 2016: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
• Keywords: 大気重力波 / 電波掩蔽 / 金星 / 重力波 / あかつき / 対流 / 数値モデル / 火星 / 数値シミュレーション / 惑星 / 大気

Outline of Final Research Achievements

Radio occultation observation data of Venus was analyzed by radio holography method to improve the vertical resolution, and universal existence of waves and neutral layers with vertical scales of several hundred meters were revealed. Sharp inversion layers were also found to exist at the top of high latitude convection layers. We also carried out numerical simulations of the convective layer with high vertical resolution and a wide computational domain, and reproduced the convective motion and the gravity waves excited by convection. Breaking of gravity waves is suggested to be caused by shear instability and convective instability. Furthermore, we could understand the height of breaking of gravity waves and the amplitude of gravity waves in comparison with the observational results of radio wave occultation observation.

Academic Significance and Societal Importance of the Research Achievements

地球をはじめ惑星大気に普遍的に存在して大気構造や気候形成に影響を与える内部重力波について、金星と地球の比較により研究を進めた。電波掩蔽観測の新たな手法により従来とらえられなかった微細構造を明らかにすることにより、金星においても地球と同様な詳細な解析が可能となった。また数値シミュレーションにより観測結果を再現して背後のメカニズムの理解を深めることができた。

Research Products

• [Journal Article] Planetary-scale streak structure reproduced in high-resolution simulations of the Venus atmosphere with a low-stability layer (2019)
  • Author(s): Hiroki Kashimura, Norihiko Sugimoto, Masahiro Takagi, Yoshihisa Matsuda, Wataru Ohfuchi, Takeshi Enomoto, Kensuke Nakajima, Masaki Ishiwatari, Takao M. Sato, George L. Hashimoto, Takehiko Satoh, Yoshiyuki O. Takahashi & Yoshi-Yuki Hayashi
  • Journal Title: Nature Communications Volume: 10 Pages: 23-23
  • NAID: 120006551679
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Morphology and Dynamics of Venus's Middle Clouds With Akatsuki/IR1 (2019)
  • Author(s): Peralta J.、Iwagami N.、Sanchez‐Lavega A.、Lee Y. J.、Hueso R.、Narita M.、Imamura T.、Miles P.、Wesley A.、Kardasis E.、Takagi S.
  • Journal Title: Geophysical Research Letters Volume: 46 Issue: 5 Pages: 2399-2407
  • DOI: 10.1029/2018gl081670
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Stationary features at the cloud top of Venus observed by Ultraviolet Imager onboard Akatsuki (2019)
  • Author(s): Takehiko Kitahara, Takeshi Imamura, Takao M. Sato, Atsushi Yamazaki, Yeon Joo Lee, et al.
  • Journal Title: J. Geophys. Res. Volume: 印刷中 Issue: 5 Pages: 1266-1281
  • DOI: 10.1029/2018je005842
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Fine vertical structures at the cloud heights of Venus revealed by radio holographic analysis of Venus Express and Akatsuki radio occultation data (2018)
  • Author(s): Imamura, T., Miyamoto, M., Ando, H., Huausler, B., Puatzold, M., Tellmann, S., Tsuda, T., Aoyama, Y., Murata, Y., Takeuchi, H., Yamazaki, A., Toda, T., Tomiki, A.
  • Journal Title: J. Geophys. Res. Volume: 123 Issue: 8 Pages: 2151-2161
  • DOI: 10.1029/2018je005627
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Local Time Dependence of the Thermal Structure in the Venusian Equatorial Upper Atmosphere: Comparison of Akatsuki Radio Occultation Measurements and GCM Results (2018)
  • Author(s): Ando Hiroki、Takagi Masahiro、Fukuhara Tetsuya、Imamura Takeshi、Sugimoto Norihiko、Sagawa Hideo、Noguchi Katsuyuki、Tellmann Silvia、Paetzold Martin、Haeusler Bernd、Murata Yasuhiro、Takeuchi Hiroshi、Yamazaki Atsushi、Toda Tomoaki、Tomiki Atsushi、Choudhary Rajkumar、Kumar Kishore、Ramkumar Geetha、Antonita Maria
  • Journal Title: Journal of Geophysical Research: Planets Volume: 123 Issue: 9 Pages: 2270-2280
  • DOI: 10.1029/2018je005640
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki (2017)
  • Author(s): Takeshi Imamura, Hiroki Ando, Silvia Tellmann, Martin Patzold, Bernd Hausler, Atsushi Yamazaki, Takao M. Sato, Katsuyuki Noguchi, Yoshifumi Futaana, Janusz Oschlisniok, Sanjay Limaye, R. K. Choudhary, Takumi Abe and Masato Nakamura
  • Journal Title: Earth, Planets and Space Volume: 69:137 Issue: 1 Pages: 1-11
  • DOI: 10.1186/s40623-017-0722-3
  • NAID: 120006486821
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Mean meridional circulation in the Venus upper atmosphere (2019)
  • Author(s): Takagi, M., N. Sugimoto, H. Kashimura, H. Ando, and Y. Matsuda
  • Organizer: Symposium on Planetary Science 2019
  • Int'l Joint Research
• [Presentation] 対流モデルに向けた金星の雲生成に関する物理計算プログラムの開発 (2019)
  • Author(s): 福原望
  • Organizer: 松江工業高等専門学校情報工学科 卒業論文
• [Presentation] Theoretical study of the Venus cloud by a general circulation model (2018)
  • Author(s): Ando, H., M. Takagi, N. Sugimoto, H. Sagawa, Y. Matsuda
  • Organizer: AGU 2018
  • Int'l Joint Research
• [Presentation] Super-rotation from Venus observations (2018)
  • Author(s): Takeshi Imamura
  • Organizer: Understanding the Diversity of Planetary Atmospheres (ISSI Workshop)
  • Int'l Joint Research / Invited
• [Presentation] A Three-dimensional Numerical Simulation of Venus' Cloud-level Convection (2018)
  • Author(s): Sugiyama, K., Odaka, M., Nakajima, K., Ishiwatari, M., Imamura, T., Hayashi, Y.-Y.
  • Organizer: JpGU 2018
  • Int'l Joint Research
• [Presentation] Structure in Venus' sub-cloud atmosphere revealed by Akatsuki radio occultation experiments (2018)
  • Author(s): Takeshi Imamura, Hiroki Ando, Katsuyuki Noguchi, Silvia Tellmann, Martin Patzold, Bernd Hausler, R. K. Choudhary
  • Organizer: JpGU 2018
  • Int'l Joint Research
• [Presentation] Initial results of the radio occultation experiment in the Venus orbiter mission Akatsuki (2017)
  • Author(s): Takeshi Imamura, Hiroki Ando, Katsuyuki Noguchi, Silvia Tellmann, Martin Patzold, Bernd Hausler, R. K. Choudhary
  • Organizer: EPSC 2017
  • Int'l Joint Research
• [Presentation] Radio holographic analysis of Venus radio occultation data (2017)
  • Author(s): Takeshi IMAMURA, Mayu MIYAMOTO, Hiroki ANDO, Bernd HAUSLER, Martin PATZOLD, Silvia TELLMANN, Toshitaka TSUDA, Yuichi AOYAMA
  • Organizer: AOGS 2017
  • Int'l Joint Research
• [Presentation] あかつき電波掩蔽観測の初期結果 (2016)
  • Author(s): 今村 剛, 安藤 紘基
  • Organizer: 地球電磁気・地球惑星圏学会 第140回総会・講演会
  • Place of Presentation: 州大学伊都キャンパス
  • Year and Date: 2016-11-19
• [Presentation] 金星探査機「あかつき」による電波掩蔽観測 (2016)
  • Author(s): 今村 剛、安藤 紘基
  • Organizer: 日本地球惑星科学連合2016年大会
  • Place of Presentation: 幕張メッセ
  • Year and Date: 2016-05-22
• [Presentation] 電波掩蔽データの電波ホログラフィ解析で明らかになった金星大気温度の微細構造 (2016)
  • Author(s): 宮本 麻由、今村 剛
  • Organizer: 日本地球惑星科学連合2016年大会
  • Place of Presentation: 幕張メッセ
  • Year and Date: 2016-05-22
• [Presentation] 雲解像モデルを用いた金星大気重力波の２次元数値実験 (2016)
  • Author(s): 安藤 紘基、杉山 耕一朗、小高 正嗣、中島 健介、今村 剛、林 祥介
  • Organizer: 日本地球惑星科学連合2016年大会
  • Place of Presentation: 幕張メッセ
  • Year and Date: 2016-05-22