日本地球惑星科学連合2014年大会

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インターナショナルセッション(口頭発表)

セッション記号 A (大気海洋・環境科学) » A-AS 大気科学・気象学・大気環境

[A-AS02_29AM1] Data Assimilation in Earth Sciences

2014年4月29日(火) 09:00 〜 10:45 314 (3F)

コンビーナ:*石川 裕彦(京都大学防災研究所)、余田 成男(京都大学大学院理学研究科地球惑星科学専攻)、榎本 剛(京都大学防災研究所)、パク ソンキ(梨花女子大学)、呉 俊傑(国立台湾大学)、宮崎 真一(京都大学理学研究科)、石川 洋一(海洋研究開発機構)、座長:石川 洋一(海洋研究開発機構)

10:00 〜 10:15

[AAS02-04] 海洋大循環モデルの接線型・アジョイントコードを用いた北太平洋中層水の移動経路特定

*藤井 陽介1中野 俊也2碓氷 典久1松本 聡2辻野 博之1蒲地 政文1 (1.気象研、2.気象庁)

キーワード:Adjoint, Sensitivity analysis, North Pacific Intermediate Water, Kuroshio Extension, Oyashio

We develops a strategy of tracing a target water mass, and applies it for analyzing the pathway of the North Pacific Intermediate Water (NPIW) from the subarctic gyre to the northwestern part of the subtropical gyre south of Japan in a simulation of an ocean general circulation model. This strategy estimates the pathway of the water mass that travels from an origin to a destination area during a specific period using a conservation property concerning tangent linear and adjoint models. In our analysis, a large fraction of the low salinity origin water mass of NPIW initially comes from the Okhotsk and Bering Seas, meets at the southeastern side of the Kuril Islands, and is advected to the Mixed Water Region (MWR) by the Oyashio current. It then enters into the Kuroshio Extension (KE) around the first KE ridge, and is advected eastward by the KE current. It, however, deviates southward from the KE axis around 158E over the Shatsky Rise, or around 170E on the western side of the Emperor Seamount Chain, and enters into the subtropical gyre. It is finally transported westward by the recirculation flow. This pathway corresponds well to the shortcut route of NPIW from MWR to the region south of Japan inferred from the analysis of the long-term freshening trend of NPIW observation.