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

根据现有的气候资料《世界海洋地图集》估计了沿137°E观测到的水域的起源，以勾勒出构成亚热带永久斜斜的水域。通过对原始高分辨率水文气候学的构建和分析，确定了副热带模态水（STMW）、中央模态水（CMW）和东部副热带模态水的源区，并揭示了它们的形成机制。一个值得注意的发现是，CMW的低位涡是由小的“交叉等压流”而不是大的“侧向诱导”引起的。副热带锋的形成主要受西南平流的影响。相似的原始气候学也揭示了亚北极背斜双温水的源区和平流路径。在一年半的时间里，我们成功地在CMW岩心对应的等平面上放置了剖面浮子，完成了CMW的准拉格朗日观测。建立了一维拉格朗日混合层模型来模拟俯冲过程，并与拟拉格朗日数据进行了比较。通过对双热水形成过程的模拟，验证了该模型的有效性。R/V Hakuho-Maru在北太平洋中部包括CMW源区的密集水文测量中，收集了混合层水向永久斜斜俯冲的冬末期后的多变量天气资料。通过对所有Argo浮子资料的分析，发现厚模态水的形成与深永久斜斜和反气旋涡旋有关，障壁层的形成与副热带南部环流高盐度水的俯冲有关。

Origins of waters observed along 137°E were estimated based on the available climatological data, the World Ocean Atlas, to outline waters composing the subtropical permanent pycnocline. The original high-resolution hydrographic climatology was then constructed and analyzed to identify the source regions of Subtropical Mode Water(STMW), Central Mode Water(CMW) and Eastern Subtropical Mode Water and to reveal their formation mechanism. One of noticeable findings is that the low potential vorticity of CMW is caused by small "cross-isopycnal flow" rather than large "lateral induction." It was also revealed that southwestward advection of STMW and CMW contribute to the formation of the subtropical fronts. The similar original climatology also revealed the source region and the advection path way of the dichothermal water in the subarctic pycnocline.Quasi-Lagrangian observations of CMW for the periods over one and half years were successfully done using the profiling floats parking at isopycnal surfaces corresponding to the CMW cores. A one-dimensional mixed layer model of the Lagrangian-type was developed to simulate the subduction processes to be compared with the quasi-Lagrangian data. The effectiveness of the model was confirmed by simulating the formation of the dichothermal water successfully.The intense hydrographic survey in the central North Pacific including the source region of CMW was conducted by R/V Hakuho-Maru to collect multi-variable synoptic data just after the late winter period during which the subduction of the mixed layer water to the permanent pycnocline occurs.All the available Argo float data were analyzed to reveal that the thick mode waters are formed associated with the deep permanent pycnocline associated with anticyclonic eddies and that the barrier layers are formed associated with the subduction of high-salinity water in the southern subtropical gyre.