[A-CG43] 黒潮大蛇行

[ACG43-04] 生物地球化学的視点からみた黒潮大蛇行

*林田 博士¹、Kiss Andrew²、美山 透¹、宮澤 泰正¹、安中 さやか³ (1.海洋研究開発機構、2.オーストラリア国立大学、3.東北大学)

キーワード：数値モデリング、東経137度定線

The large meander of the Kuroshio western boundary current is well known to influence the local climate, fisheries, and aquaculture by greatly modulating regional heat transport, but its impacts on biogeochemical processes remain unclear. Using high-resolution numerical ocean modelling and long-term observational datasets, we show that the path of the Kuroshio determines the extent of the shallow nutricline region, where winter convective mixing replenishes nutrient availability for subsequent blooms of phytoplankton during spring. During the large meander phase, this mechanism triggers offshore phytoplankton blooms that are otherwise absent during the non-large meander phase. The large meander also modulates the spatial distributions of primary production, air-sea carbon flux, and export production. These biogeochemical impacts of the Kuroshio large meander exert bottom-up control on regional marine ecosystems that is disproportionate to the thermal effect, and therefore need to be assessed to understand the large meander’s overall impacts on fisheries and aquaculture.