Arctic marine environments regulated by ocean transport and air‒sea‒land interaction: Findings from the ArCS II Ocean Research Program

The second phase of the Arctic Challenge for Sustainability (ArCS II) project funded by the Japanese government was launched in June 2020. The Ocean Research Program of this project was engaged in research on Arctic marine environments and production of corresponding public datasets. Sub-program 1 was established to explore ocean heat/freshwater transport and biogeochemical cycles in seasonal and multi-year sea ice zones. Sub-program 2 focused on assessment of the vulnerability and resilience of marine ecosystems in response to rapid sea ice retreat. Sub-program 3 examined air–sea interactions related to sea ice and waves. The expected outcomes included refinement of Earth System Models, advancement of ecosystem-based fishery management, and development of safer maritime navigation. This article compiles the major findings of sub-programs 1 and 3, together with brief summaries on the research cruises, sea ice field campaigns, and modeling experiments conducted through various international collaborations. The scientific achievements of the ArCS II research activities foster a deeper understanding of the effects of climate change and provide information for socioeconomic benefit.