Development of a Venusian non-hydrostatic atmospheric general circulation model for exploring the role of thermal convection in large-scale structures in the cloud layer

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K04062
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17020:Atmospheric and hydrospheric sciences-related
• Research Institution: Kobe University
• Principal Investigator: Kashimura Hiroki 神戸大学, 理学研究科, 講師 (80635186)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 金星大気 / 全球非静力学モデル / 高解像度シミュレーション / 鉛直対流 / 季節依存性

Outline of Final Research Achievements

A global non-hydrostatic model of the Venusian atmosphere was developed, and the first global high-resolution simulation explicitly representing small-scale vertical convection in the cloud layer was performed to demonstrate the importance of vertical convection. With a thermal forcing that leads to a statically unstable state, the simulated stability became consistent with the observed value, but the superrotation was reduced by half. Our simulation showed that obtaining both a realistic stability profile and superrotation is a problem we need to address. We also carried out an experiment where we introduced a tilt of about 2.6 degrees to the axis of planetary rotation. This experiment showed that significant seasonal variations also exist in the Venusian atmospheric circulation, and that their characteristics are qualitatively consistent with those of the Earth's seasonal variations.

Free Research Field

惑星気象学

Academic Significance and Societal Importance of the Research Achievements

本研究の学術的意義は、以下の３点である。（１）これまで静力学平衡を仮定した数値モデルで議論されてきた金星大気循環に対して、全球非静力学モデルという次世代型の数値モデルを提供したこと。（２）金星大気シミュレーションにおいて、雲層高度の安定度とスーパーローテーションの両立という新たな課題を露わにしたこと。（３）これまで見過ごされてきた、大気循環に対する自転軸の傾きの影響（季節依存性）を明確に示したこと。また本研究の社会的意義は、日本の金星探査機「あかつき」の成果に寄与し、日米欧でそれぞれ検討計画されている次期金星探査に資することで、国際貢献に繋がっている点である。