[A-OS15] Marine ecosystems and biogeochemical cycles: theory, observation and modeling

[AOS15-03] Kuroshio's West Wall

*Chen-Tung Arthur Chen¹, Ting-Hsuan Huang¹, Xinyu Guo², Min Yang³ (1.Department of Oceanography, National Sun Yat-sen University, Kaohsiung 804, Taiwan, 2.Center for Marine Environmental Studies, Ehime University, 2-5 Bunkyo-Cho, Matsuyama 790-8577, Japan, 3.State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China)

Keywords:Kuroshio, West Wal, Kuroshio Extension, Western Intensification, South China Sea, East China Sea

Although it is well known that there is a so-called Gulf Stream North Wall in the Atlantic Ocean, the Kuroshio's West Wall has never been reported. Rather than rock solid, the "Wall" is a dynamic interface marking the westernmost extent of the Kuroshio's warm, fast-moving waters before transitioning into the Kuroshio Extension Current. The West Wall is a region of significant thermal gradients in winter, with warm subtropical waters to the east juxtaposed against lower temperate waters to the west. Further, surface waters east of the Wall have high salinity and are oligotrophic, while surface waters west of the Wall are fresher and nutrient-rich year-round. This is because the east of the Wall contains waters from the nutrient-depleted subtropical North Pacific Ocean.
In contrast, the West includes waters from the East and South China Seas with more prominent influences from the land. These strong contrasts create a zone of heightened oceanographic activity, including mesoscale eddies, filaments, intense vertical mixing, and significant nutrient upwelling. Additionally, the Wall supports diverse marine ecosystems, serving as a corridor for migratory species and a hotspot for biological productivity. Understanding these dynamics is crucial for predicting regional and global climate impacts and managing fisheries and marine biodiversity effectively.