北太平洋風成循環流の季節変化に関する数値モデル実験

• Main Authors: 舘野, 愛実, 藤原, 将平, 磯田, 豊, 朝日, 啓二郎
• Format: Article in Journal/Newspaper
• Language: Japanese
• Published: 北海道大学大学院水産科学研究院
• Subjects: wind-driven circulation; two-layer model; seasonal variation; barotropic and baroclinic response; bathymetry; 660; Pacific; Western Shelf; Subarctic
• Online Access: http://hdl.handle.net/2115/64173; https://doi.org/10.14943/bull.fish.66.3.87

A two-layer model ocean with Izu-Ogasawara Ridge(IOR) and the Emperor Seamounts(ESs), driven by seasonally varying wind stress, is used to explain the observed seasonal variations of barotropic and baroclinic response in the North Pacific. Since isostasy is achieved for annual mean state, the annually averaged subarctic and subtropical surface gyres are separated without any bathymetric influence. For a short time scale such as seasonal variation, the barotropic flow is inhibited from ascending the bottom slope because of the restriction of the potential vorticity conservation, and generates the baroclinic Annual Rossby Waves(ARW) through the impinging process on the shelf slope. The most conspicuous feature in barotropic response is the southward invasion of the subarctic anti-clockwise circulation strengthened in winter into the subtropical region along the IOR and the western shelf slope. It is also found that the westward propagating baroclinic ARW from the southern ESs is appeared to be enhanced in spring by superimposing on the seasonal change of Ekman pumping. These model results are consistent with those estimatied from the observation.