SUBDUCTION PROCESSES IN THE NORTH PACIFIC BASED ON ANALYSES OF HIGH-QUALITY DATA

北太平洋的年俯冲率是根据等密度平均水文气候学、高分辨率冬季混合层气候学以及来自船舶报告、数值天气预报产品和卫星产品的各种风应力气候学计算的。在位温-盐度（θ-S）空间中比较了永久密度跃层的俯冲速率和体积，发现永久密度跃层下部的θ-S关系与冬季混合层俯冲水的θ-S关系不同，前者系统性地比后者更暖、更咸。这一特征与冬季混合层俯冲水直接维持永久密度跃层θ-S关系的经典观点不一致，通过考察航行和剖面浮标观测，证实了混合层水俯冲的副热带-副北极过渡区锋面结构 ...更多信息 艾德引入永久密度跃层下部，在确定永久密度跃层的θ-S关系中起着至关重要的作用。我们发现，在密度补偿温盐锋极向一侧的深层混合层形成了垂直均匀的水团，其温度和盐度低于中心模式水（CMW），但密度与中心模式水（CMW）几乎相同，我们称之为过渡区模式水（TRMW）。早春，锋面向赤道一侧较暖、较咸的海水向TRMW扩散，导致TRMW顶部附近活跃的盐指运动，使TRMW在几个月内转化为CMW，从而使永久密度跃层的θ-S关系得以维持。这将成为详细了解永久密度跃层的结构和起源以及为长期气候预测开发海洋环流模型和物质循环模型的基础。少

The annual subduction rate of the North Pacific was calculated based on isopycnally averaged hydrographic climatology, high-resolution winter mixed-layer climatology, and various wind stress climatologies from ship reports, numerical weather prediction products, and satellite products. The subduction rate and the volume of the permanent pycnocline were compared in potential temperature-salinity (θ-S) space, revealing that the θ-S relation of the lower permanent pycnocline is different from that of the water subducted from winter mixed layer; the former is systematically warmer and saltier than the latter. This feature is not consistent with the classical view that the θ-S relation of the permanent pycnocline is directly maintained by the water subducted from the winter mixed layer.Conducting the research cruises and the profiling float observations, it was demonstrated that the frontal structure in the subtropical-subarctic transition region, from which the mixed layer water is subduct … More ed into the lower permanent pycnocline, plays an essential role in determining the θ-S relation of the permanent pycnocline as follows. We found that the deep mixed layer on the poleward side of the density-compensating temperature and salinity front forms vertically homogeneous water mass which has lower temperature and salinity than but almost the same density as Central Mode Water (CMW) and called this water mass Transition Region Mode Water (TRMW). In early spring, the warmer and saltier water on the equatorward side of the front spreads over TRMW, causing active salt fingering near the top of TRMW, which transform TRMW into CMW within a few to several months.This study presents an essential mechanism by which the θ-S relation of the permanent pycnocline is maintained, which will serve as the basis for detailed understanding of the structure and origin of the permanent pycnocline and development of ocean general circulation models and material cycle models for long-term climate prediction. Less