[A-CG30] 中緯度大気海洋相互作用

[ACG30-P01] Simulated decadal variations of surface and subsurface phytoplankton in the upstream Kuroshio Extension region

*東塚 知己^1,2、笹井 義一²、安中 さやか³、佐々木 英治²、野中 正見² (1.東京大学大学院理学系研究科地球惑星科学専攻、2.海洋研究開発機構、3.東北大学)

キーワード：植物プランクトン、黒潮続流、十年規模変動、海洋生態系モデル

Using outputs from an ecosystem model embedded in an eddy-resolving ocean general circulation model that can realistically simulate decadal modulations of the Kuroshio Extension (KE) between stable and unstable states, decadal variations of phytoplankton concentration in the upstream KE region are investigated. During stable states of the KE, surface phytoplankton concentrations are anomalously suppressed to the south of the KE front, while those to the north are anomalously enhanced. Although the surface phytoplankton concentration anomalies are prominent only during winter to spring, significant subsurface anomalies centered around 60 m depth persist even in summer and autumn. Anomalies persist throughout the year in phytoplankton biomass integrated over the upper 100 m despite the strong surface anomalies during the spring bloom season. An analysis of nitrogen concentration anomalies suggests that the vertical movement of the isopycnal surfaces, vertical mixing of nutrients, and meridional shifts in the KE jet contribute to the anomalous phytoplankton biomass.