2023 Fiscal Year Final Research Report
Interannual to decadal variations of oceanic submesoscale motions in the Kuroshio Extension region
| Project/Area Number |
20K04075
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 17020:Atmospheric and hydrospheric sciences-related
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| Research Institution | Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
Sasaki Hideharu 国立研究開発法人海洋研究開発機構, 付加価値情報創生部門(アプリケーションラボ), 主任研究員(シニア) (50359220)
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| Co-Investigator(Kenkyū-buntansha) |
笹井 義一 国立研究開発法人海洋研究開発機構, 地球環境部門(地球表層システム研究センター), 主任研究員 (40419130)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | 海洋微細循環 / 経年変動 / 高解像度海洋モデル / 混合層不安定 |
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| Outline of Final Research Achievements |
We aim to reveal the interannual variations of oceanic submesoscale circulations by using the outputs from a hindcast simulation of a high-resolution ocean model. The submesoscale circulations are active in winter caused by baroclinic instability within the mixed layer. In the subtropical northeastern Pacific, the submesoscale circulations are more active in the El Nino winter than in other winters, due to the enhanced instability. The mixed layer depth in winter is relatively shallow in the Kuroshio Extension region compared to the surrounding areas, which is due to the restratification induced by submesoscale circulations. Based on the estimation of the instability intensity from mixed layer depth and surface density gradient, there is a possibility that the variations of submesoscale circulations are estimated from the observation data at a relatively coarse resolution.
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| Free Research Field |
海洋物理
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| Academic Significance and Societal Importance of the Research Achievements |
本研究では、黒潮続流域などで冬季に活発になる微細循環の経年変動を高解像度の海洋モデルの出力で示し、亜熱帯北東太平洋域ではエルニーニョ年に微細循環が活発になることを示した。さらに傾圧不安定の強度を推定することで、解像度が粗い観測データでも、微細循環の時空間変動を推定しうる手法を提案した。これらの結果は、温暖化を含む気候変動が海洋表層の傾圧不安定の強度に影響を及ぼすことで冬季の微細循環が時空間的に変動し、その変動が中規模渦や海流などの大循環や生態系を含む物質循環まで影響が及ぶことを示唆している。
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