Japan Geoscience Union Meeting 2023

Presentation information

[E] Online Poster

A (Atmospheric and Hydrospheric Sciences ) » A-CG Complex & General

[A-CG30] Extratropical oceans and atmosphere

Mon. May 22, 2023 1:45 PM - 3:15 PM Online Poster Zoom Room (2) (Online Poster)

convener:Shion Sekizawa(Research Center for Advanced Science and Technology, University of Tokyo), Shota Katsura(Atmosphere and Ocean Research Institute, The University of Tokyo), Yuta Ando(Kyushu University), Shoichiro Kido(JAMSTEC Application Lab)


On-site poster schedule(2023/5/21 17:15-18:45)

1:45 PM - 3:15 PM

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

*Tomoki Tozuka1,2, Yoshikazu Sasai2, Sayaka Yasunaka3, Hideharu Sasaki2, Masami Nonaka2 (1.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 2.JAMSTEC, 3.Tohoku University)

Keywords:Phytoplankton, Kuroshio Extension, Decadal variation, Ecosystem model

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.