日本地球惑星科学連合2023年大会

講演情報

[E] 口頭発表

セッション記号 A (大気水圏科学) » A-CG 大気海洋・環境科学複合領域・一般

[A-CG30] 中緯度大気海洋相互作用

2023年5月21日(日) 13:45 〜 15:00 201A (幕張メッセ国際会議場)

コンビーナ:関澤 偲温(東京大学先端科学技術研究センター)、桂 将太(東京大学大気海洋研究所)、安藤 雄太(九州大学)、木戸 晶一郎(海洋開発研究機構 付加価値創生部門 アプリケーションラボ)、座長:木戸 晶一郎(海洋開発研究機構 付加価値創生部門 アプリケーションラボ)、安藤 雄太(鈴鹿工業高等専門学校)


14:00 〜 14:15

[ACG30-07] Dominant forcing regions of decadal variations in the Kuroshio Extension revealed by a linear Rossby wave model

*田村 優樹人1東塚 知己1 (1.東京大学)


キーワード:黒潮続流、10年規模変動、ロスビー波、海面高度、北太平洋

The Kuroshio Extension (KE) is an intense eastward oceanic jet in the midlatitude western North Pacific. Due to active ocean-atmosphere interactions over the strong oceanic front associated with the KE, the area may be a key region for basin-scale Pacific climate variability. Satellite altimeters and eddy-resolving ocean models have revealed that the KE undergoes large decadal variations between a stable state and an unstable state, especially after the 1976/77 climate regime shift. Although previous studies suggested that baroclinic Rossby waves induced in the central and/or eastern North Pacific reach the KE and influence the KE decadal variability, it is still unclear where and how decadal surface atmospheric forcing anomalies that excite the Rossby waves are generated. In this study, using a linear Rossby wave model forced by reanalysis surface wind stress, the relative contribution of wind stress at each longitude is quantitatively investigated for the first time. It is shown that the wind forcing in the central North Pacific around 160°-150°W makes the largest contribution to the KE decadal variability. Further analyses suggest that the anomalous atmospheric forcing is caused by El Niño/Southern Oscillation (ENSO) Modoki via an atmospheric teleconnection, and the statistically significant relationship between the KE and ENSO Modoki appears only after the regime shift.