Studies on the water-mass formation and temperature determination in the Kuroshio and Kuroshio Extension regions

利用该基金，我们引进了一种低流速声学多普勒海流剖面仪（LADCP）。我们开发了一个数据处理算法LADCP与CTD数据，是准确的几厘米/秒。利用LADCP，我们于1999年7月、1999年8 - 9月、2000年2 - 3月、2000年11月、2001年1 - 2月在西北太平洋进行了一系列观测，两年共获得了180多天、450多个测站的LADCP资料。这种密集和广泛的LADCP观测对世界海洋学界来说是了不起的。利用LADCP和CTD资料，我们发展了一种分析方法来估算调整后的地转速度和垂直混合系数。我们应用这些新方法来量化地表和地下环流，产生了大量的结果和出版物。本文发展了一种假定准地转动力学的垂直速度分析方法，得到了沿着等密度面的大垂直速度和黑潮延伸体的表面-次表面相互作用和沿着俯冲的结果。通过对历史资料的分析，发现世纪初黑潮延伸区海温的年代际变化与下半叶相似。结合历史资料和整体混合层模式，阐明了黑潮及其延伸体的热量输送对SST的重要性。混合层深度和温度的制度转变检测和混合层深度的变化前几年的SST转变。80年代后期的变化是混合层变化和热输送共同作用的结果。从海洋环流模式，热量输送的黑潮也被认为是至关重要的温度。

We introduced Lowered Acoustic Doppler Current Profiler (LADCP) by this grant. We developed a data processing algorithm for LADCP with CTD data that is as accurate as a few cm/sec. With this LADCP, we performed a series of observations in the northwestern Pacific in July 1999, August-September 1999, February-March 2000, October-November 2000, January-February 2001, in which we obtained total observations amounted to be over 180days and over 450 stations of LADCP data in two years. This intensive and extensive LADCP observations are remarkable for the world oceanographic community. Using these LADCP and CTD data, we developed a analysis method for estimating adjusted geostrophic velocity and vertical mixing coefficients. We applied these new methods to quantifying surface and subsurface circulations to produce a large number of results and publications. We developed a analysis method of vertical velocity assuming quasi-geostrophic dynamics, and we obtained results of large vertical velocities along isopycnal surface and surface-subsurface interaction and subduction along the Kuroshio Extension. We also performed historical data analyzes; in early 20th century the interdecadal SST variations occurred in the Kuroshio Extension regions as in late half. With historical data combined with bulk mixed layer models, we clarified the importance of heat transport by the Kuroshio and Kuroshio Extension on the determination of SST. Regime shifts of mixed layer depths and temperature were detected and the change of mixed layer depth a few years preceded the SST shift. The shifts in late 1980s are suggested to be due to the combinations of shifts in mixed layer and heat transport. From oceanic general circulation models, heat transport by the Kuroshio is also suggested to be crucial for temperature.