Habitable Japan Sustainability of atmospheric and oceanic environment as a survival basis of island country Japan Grant-in-Aid for Transformative Research Areas (A) (2024–2028)

The Kuroshio Current plays an important role in shaping the mild climate around Japan and nurturing abundant living marine resources. However, in the Kuroshio region, along with the rapid ocean warming, a different regime has begun to emerge in recent years, such as the historically long-lasting Kuroshio large meander and frequent marine heatwaves. In this project we focus on ocean extremes such as the Kuroshio large meander, marine heatwaves, and coastal extremes, and aim to comprehensively understand their physical mechanisms, predictability, future changes, and impacts on living marine resources by conducting the following research items:

1. We assess the predictability of ocean extremes using an ensemble approach by Kuroshio forecasting systems.
2. We explore long-term changes in ocean extremes from the past to the future using long-term ocean reanalysis data and future ensemble simulations with a high-resolution ocean model.
3. We investigate the three-dimensional distribution and supply processes of nutrients to determine the effects of ocean extremes on the productivity of phytoplankton.
4. We analyze data on egg and larval surveys for pelagic fish and describe the relationships between ocean extremes and the key fluctuation processes of living marine resources, such as the formation of spawning grounds and larval survival.
5. By synthesizing the results of the above research items, we describe the impacts of changes in the oceanic environment associated with ocean extremes on living marine resources.