Research Project
Grant-in-Aid for Early-Career Scientists
金星は地球の双子星だが全く異なる気候進化を遂げた.その大きな要因である厚い硫酸雲を探査機と地上望遠鏡から観測的に調べる.研究は3つの小課題に分けて実施する.まず,探査機「あかつき」の2μmカメラ画像から雲の高度や厚みの緯度及び地方時依存性を明らかにする.また雲構造を変化させる大気運動を調べるため,鉛直運動の指標となる一酸化炭素分布を推定し雲追跡手法で得られる水平風との関係を調査する.さらに,地上望遠鏡を用いた近赤外高分散分光観測から雲形成や大気運動の指標となる微量大気の時空間変動を調べる.研究成果は大気大循環モデルやデータ同化手法による大気現象の再現や気候システムの解明に必要な制約情報となる.
Optically thick clouds of sulfuric acid on Venus were observationally investigated by new observations using Akatsuki spacecraft and a ground-based telescope, IRTF. From near-infrared images of Akatsuki, the cloud tops were found to have an equatorially symmetric structure. The average cloud top altitude showed a gradual decrease from low to mid latitudes. It rapidly dropped from mid to high latitudes. The cloud tops on Venus are basically stable for nearly ten years in light of previous studies using past spacecraft data. The stationary gravity wave features first discovered in mid-infrared images of Akatsuki were also seen in the near-infrared images. The bright contrast of the features could be interpreted as resulting from the difference in cloud top altitude of a few hundred meters. The cloud tops derived from CO2 lines obtained by a high-resolution infrared spectroscopy using IRTF qualitatively supported the results from the near-infrared images of Akatsuki.
全球を覆う光学的に厚い硫酸雲は金星全体の熱収支を支配しており,この振る舞いが金星の気候進化に大きく影響してきたと考えられる.従って,雲層構造の空間分布とその時間変動の理解は,金星の気候システムを解明する上で重要な基礎情報となる.本研究では,欧州探査機Venus Express以降では唯一となる雲層の詳細観測を実施した探査機「あかつき」と地上望遠鏡による観測データを用いて,雲頂高度分布と山岳波に起因した定在構造を含む微細構造について新たな知見を得た.これらは大気大循環モデルやデータ同化手法による大気現象の再現や気候システムの解明に必要な制約情報となった.
All 2023 2022 2021 2020 2019
All Journal Article (10 results) (of which Int'l Joint Research: 7 results, Peer Reviewed: 10 results, Open Access: 7 results) Presentation (16 results) (of which Int'l Joint Research: 8 results, Invited: 4 results)
Icarus
Volume: 390 Pages: 115307-115307
10.1016/j.icarus.2022.115307
Journal of Geophysical Research: Planets
Volume: 127 Issue: 6
10.1029/2022je007228
Proceedings of SPIE - The International Society for Optical Engineering
Volume: 12264 Pages: 18-18
10.1117/12.2638444
J. Geophys. Res.: Planets
Volume: 126 Issue: 10
10.1029/2020je006808
Nature
Volume: 595 Issue: 7868 Pages: 511-515
10.1038/s41586-021-03636-7
Volume: 355 Pages: 114134-114134
10.1016/j.icarus.2020.114134
Science
Volume: 368 Issue: 6489 Pages: 405-409
10.1126/science.aaz4439
120006863171
Volume: 345 Pages: 113682-113682
10.1016/j.icarus.2020.113682
Geophysical Research Letters
Volume: 46 Issue: 16 Pages: 9457-9465
10.1029/2019gl083820
Volume: 46 Issue: 14 Pages: 7955-7961
10.1029/2019gl083311