Understanding of the role of ocean vertical heat transport process on heat uptake efficiency in the climate system

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K04077
• 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: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: Suzuki Tatsuo 国立研究開発法人海洋研究開発機構, 地球環境部門(環境変動予測研究センター), グループリーダー代理 (10415995)
• Co-Investigator(Kenkyū-buntansha): 小室 芳樹 国立研究開発法人海洋研究開発機構, 地球環境部門(北極環境変動総合研究センター), グループリーダー (90396945)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 海洋熱吸収効率 / 地球温暖化 / 海洋熱輸送 / 気候モデル / 海洋モデル

Outline of Final Research Achievements

The role of dense water mass transport to ocean-deep layers at high latitudes on ocean heat absorption in the climate system was investigated using the climate model MIROC6. The formation and spreading of dense deepwater in the polar regions play a crucial role in one of the most critical climate systems. Here, we performed a series of numerical experiments with a climate model where the downward water mass transport through the bottom boundary layer is artificially reduced to quantitatively evaluate its impacts on the transient ocean and climate responses. It is demonstrated that changes in deepwater formation have non-negligible impacts on not only ocean heat content but also the Earth's radiation budget at the top of the atmosphere: reduction in deepwater formation in high-latitude oceans causes warming of bottom water, cooling of the ocean surface, and a subsequent decrease in outgoing longwave radiation.

Free Research Field

気候物理

Academic Significance and Societal Importance of the Research Achievements

地球温暖化の人間社会への影響を抑制する取組みにおいて、海洋の熱吸収過程を正しく理解する事が求められている。本研究による海洋の熱吸収プロセスの理解は、温暖化予測に用いられる気候モデル間の気候感度の不確実性の理解と地球温暖化予測精度の向上に寄与する。さらに海洋の気候場の成り立ちとして、海洋鉛直成層の形成メカニズムの理解が進んだ。