2019 Fiscal Year Final Research Report
Quantitative investigation on uncertainty included in oceanic interannual variability forced by interannually varying atmosphere
| Project/Area Number |
17K05665
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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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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
NONAKA Masami 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), グループリーダー (90358771)
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| Co-Investigator(Kenkyū-buntansha) |
高谷 康太郎 京都産業大学, 理学部, 教授 (60392966)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | 海洋自励振動 / 潜在的予測可能性 / 海洋中規模渦 / 海洋前線 / 海洋大循環モデル / アンサンブル実験 |
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| Outline of Final Research Achievements |
In the present study, we have conducted a high-resolution (0.1-degree longitude and latitude) ocean computational simulation for the period from 1965 to 2016. Ten similar ocean simulations were conducted with observation-based atmospheric fields (wind, temperature, humidity, etc.) from slightly different initial states. Comparison of the ten simulations can show ocean variations forced by atmospheric variability and also those driven by oceanic internal dynamics.
We investigated interannual-to-decadal variability in the Kuroshio Extension (KE) jet, a strong eastward current in the western North Pacific, based on the simulations. The results show that decadal variability in the KE jet is dominated by atmospheric forcing, but its interannual variability is dominated by the oceanic internal dynamics. This means the interannual variability is chaotic and its predictability is limited. The simulation data can be used further studies of potential predictability of global ocean variability.
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| Free Research Field |
気候力学、海洋物理学
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| Academic Significance and Societal Importance of the Research Achievements |
黒潮や親潮、黒潮続流といった強い海流は多くの熱や栄養塩等を運ぶことで気候や海洋生態系に強く影響する。このため、その年々の変動の原因の理解を深め、予測を実現することは社会的にも重要である。本研究の成果から、黒潮続流の年々変動には大気変動とは関係無くカオス的に生じる変動が多く含まれることが明らかにされた。この変動は本質的に予測が不可能であり、これは黒潮続流の年々変動の予測には限度があることを意味する。この結果は今後、黒潮続流の予測を実現して行く上で重要である。その予測ではカオス的な振る舞いを前提にすることが必要となる。
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