在北极快速变化过程中，海冰覆盖范围和密集度的显著减少，相对更为稀疏的海冰使得海洋对大气强迫有不同的响应，导致上层环流结构发生变化，原有的穿极流结构正在向边界流结构转换。海洋环流转型是势必发生的现象，2010年发生的穿极流中断和未融先开现象表明了环流转型已经开始。然而，科学界对环流转型及其产生的各种变化缺乏了解和认识，急需对于转型带来的后果尤其是对气候系统的影响开展研究，本项目针对正在发生的海洋环流转型过程，开展现场观察，布放北极浮标，利用卫星遥感数据和海-冰耦合模式，研究伴随海冰变化产生的北极上层海洋环流由穿极流型向边界流型的转换，揭示洋区内海冰及物质输运的改变、海冰输出量的变化、上升运动的消失、边界流加强、中层水补偿机制的调整，并研究由此产生的海气相互作用的变化、对北极涛动强度和极性的影响。通过这些研究，了解北极快速变化的综合结果，认识海洋环流的变化在北极气候系统中的重要作用。

The Arctic is experiencing a rapid transition with the decline of sea ice concentration and ice coverage. The decreased sea ice will respond obviously the local atmospheric forcing to produce a varying upper ocean circulation. We have observed a extremely low ice concentration in central Arctic in 2010 summer, which indicates the ice openning before melding phenomenin. The changing of ice concentration is revealed as a result of a special circulation pattern of ice drifting filed, which is cyclonic one, opposite to the anticyclonic Beaufort Gyre. The pattern makes the ice in Canada Basin be transported to the Canadian Archipelago, and produce a region with very low ice concentration. The pattern is not very rare, about 16% during 1978-2006, but mostly appeared in winter. The continuously appeared cyclonic circulation patterns indicate circulation transiting from the Transpolat Drift to a boundary current system. The incontinuity of Transpolar Drift and the ice open before melting phenomena appeared in 2010 indicated the beginning of the ocean circulation transition (OCT). However, it is not sufficient to understand the OCT and varies variation in Arctic because of the OCT, especially the influence of OCT on climate system. Facing to the on-going OCT process, this project will focus on the field observation, buoy deployment, satellite remote sensing and ice-sea coupling model to study the transition of Arctic upper circulation. We will also pay more attention to study the variation of ice and material transpoetation, variation of ice export from Fram Strait, the vanish of the upwelled movement in Canada Basin, the enhanced boundary current, and the adjustment of the compensation of the intermediate water. With these results, the study will focus on the sea-ice-air coupling variation and the influence on Arcitc Oscillation. By these study, it is benefit to understand the impacts of Arctic rapid change, knowing the significant influence of ocean circulation variation on Arctic and global climate system.