Elucidation of the Delay Mechanism in the Influence of Solar Activity Variations on Earth's Climate through the Stratosphere

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K14798
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 17020:Atmospheric and hydrospheric sciences-related
• Research Institution: Kyushu University (2022-2023); Japan Agency for Marine-Earth Science and Technology (2019-2021)
• Principal Investigator: Noguchi Shunsuke 九州大学, 理学研究院, 助教 (90836313)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: 太陽活動 / 北大西洋振動 / 北極振動 / 環状モード / 成層圏-対流圏結合 / 地球システムモデル / 高エネルギー粒子降り込み / 大気海洋相互作用

Outline of Final Research Achievements

In considering the influence of solar activity variations on Earth's climate, the downward influence processes originating from stratospheric polar vortex variations play an important role. This study investigated the details of the processes by which the effects of the solar 11-year cycle on the surface manifest with a delay of 2-4 years through a series of numerical experiments using an Earth system model. The effects of energetic particle precipitation and atmosphere-ocean interactions were quantitatively evaluated through ensemble comparison experiments utilizing techniques such as partial constraint of stratospheric circulation variations. As a result, this study successfully illustrated how extreme variations in the stratospheric polar vortex drive ocean circulation, producing significant cross-year effects. This corresponds to the demonstration of the fundamental processes of the delayed response.

Free Research Field

大気科学

Academic Significance and Societal Importance of the Research Achievements

太陽活動と地球気候との関係は複雑であり、よく知られた太陽11年周期変動の影響も、単純には現れない。その間の物理過程を明確にしていくことは、現在、学術的にも社会的にも重要な課題となっている。本研究では、太陽活動の影響を受けた成層圏の変動が、数年遅れて地表応答を引き起こす様を、因果関係の明確な数値実験の枠組みを構築して、示すことに成功した。成層圏から対流圏への下方影響過程の、大気海洋相互作用の変調や上空の化学組成の変化を通じた、よりスケールの大きな地球システム変動との繋がりを、実事例で明らかできたことは、当該分野の視野拡大という点でも意義深い。