Recent advances in mid-latitude atmosphere-ocean-marine ecosystem interactions in a changing climate: From Climatic Hotspot2 to Habitable Japan

This article reviews recent achievements in the study of mid-latitude atmosphere-ocean-marine ecosystem interactions from two Japanese research programs: the Climatic Hotspot2 project (FY2019–2023) and the first two years of the Habitable Japan project (FY2024–2028). Understanding of the mid-latitude ocean-atmosphere interactions, particularly the ocean’s influence on the atmosphere established in the Climatic Hotspot1 project (FY2010–2014), has advanced through the two projects addressing changing climate and oceanic/atmospheric extreme events, such as the longest observed Kuroshio large meander from 2017 to 2025, northward meandering of the upstream Kuroshio Extension in 2023–2024, marine/atmospheric heatwaves, heavy rainfall and snowfall, and tropical cyclones. Relations between weather and its extremes over East Asia and global climate variations have also been clarified. Both projects have conducted and are conducting in-situ observation campaigns to clarify various processes in the ocean, atmosphere, and their interactions and improve numerical models. By incorporating atmospheric/marine chemistry, marine ecosystems, and fisheries as new research domains and putting more emphasis on prediction, the Habitable Japan project aims to answer the main question: Will mild climate and abundant water/fisheries resources persist as a basis of survival for those of us living in Japan in the future?