Japan Geoscience Union Meeting 2016

Presentation information

International Session (Oral)

Symbol A (Atmospheric and Hydrospheric Sciences) » A-CG Complex & General

[A-CG08] Continental-Oceanic Mutual Interaction: Global-scale Material Circulation through River * Runoff

Mon. May 23, 2016 9:00 AM - 10:30 AM A04 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Yosuke Yamashiki(Global Water Resources Assessment Laboratory - Yamashiki Laboratory Graduate School of Advanced Integrated Studies in Human Survivability Kyoto University), Yukio Masumoto(Graduate School of Science, The University of Tokyo), Yasumasa Miyazawa(Japan Agency for Marine-Earth Science and Technology), Swadhin Behera(Climate Variation Predictability and Applicability Research Group, Application Laboratory, JAMSTEC, 3173-25 Showa-machi, Yokohama 236-0001), Toshio Yamagata(Japan Agency for Marine-Earth Science and Technology), Kaoru Takara(Disaster Prevention Research Institute, Kyoto University), Chair:Yukio Masumoto(Graduate School of Science, The University of Tokyo), Swadhin Behera(Japan Agency for Marine-Earth Science and Technology), Toshio Yamagata(Japan Agency for Marine-Earth Science and Technology)

9:00 AM - 9:15 AM

[ACG08-01] How does the Amur River discharge spread over the northwestern continental shelf in the Sea of Okhotsk?

★Invited papers

*Humio Mitsudera1, Ayumi Manome2 (1.Institute of Low Temperature Science, Hokkaido University, 2.Cooperative Institute for Limnology and Ecosystems Research (CILER), University of Michigan)

Keywords:Amur River, Sea Ice Formation, Dense Shelf Water, Coastally Trapped Waves

Iron is a micro-nutrient that is necessary for photosynthesis of the phytoplankton. It is now well known that the iron transported by the Amur River is deposited on the continental shelf in the northwestern shelf of the Sea of Okhotsk, and is then transported out to the intermediate layer of the Sea of Okhotsk; it further spreads to the western North Pacific and supports phytoplankton bloom there. Despite their significance in transporting dissolved and particulate iron, however, the paths of the Amur River discharge on the continental shelf in the Sea of Okhotsk are still unknown. In this study, we conduct a coupled ice-ocean simulation for the northern Sea of Okhotsk from June 1998 to September 2000 to answer a question: Can the Amur River discharge deposit materials to the pathway of the dense shelf water? In a series of numerical experiments, we identified two routes (the western and eastern routes) that could transport the river water more than 100 km offshore over the northwestern continental shelf. The two routes share the clockwise gyre in the Sakhalin Gulf and the northeastward flow on the northwestern continental shelf. These features are connected through the westward jet along the slope from the Sakhalin Gulf (the western route), and the northward transport over the shelf break canyon (the eastern route). The river water, the dense shelf water, and the easterly wind are in a fine geophysical balance for those features, and all are required for the formation of the two routes. The model results show these unique joint effects in the Sea of Okhotsk that allow the Amur River discharge to be effectively transported over the northwestern continental shelf, unlike a general river discharge that flows along the coast, and can deposits materials into the pathway of the dense shelf water.