Publication Date:
2023-05-17
Description:
Decadal variations of phytoplankton concentrations in the upstream Kuroshio Extension (KE) region are investigated using outputs from a simple ecosystem model embedded in an eddy-resolving ocean general circulation model, which can well simulate decadal modulations of the KE between stable and unstable states. During the KE stable states, surface phytoplankton concentrations are anomalously suppressed (enhanced) to the south (north) of the KE front. Although the surface phytoplankton concentration anomalies are prominent only during winter to spring as revealed by past studies, it is shown for the first time that significant subsurface anomalies centered around 60 m depth persist even in summer and autumn. Further analyses of nitrogen concentration anomalies suggest 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. Moreover, the remarkable subsurface anomalies in phytoplankton concentration may feedback on to decadal sea surface temperature anomalies by modulating absorption of penetrative shortwave radiation.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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