Spatial-Temporal variations of the North Pacific Intermediate Water and its relationship with the large-scale atmospheric field

北太平洋中层水(NPIW)以垂直盐度最低层为特征，分布在200-1000m深度。在这项研究中，我们利用日本气象厅1972-2008年进行的137E子午线上的重复水文断面，研究了NPIW地区的时间特征。NPIW面积的变化表现出明显的准年代际(约10年)的调制。利用风驱动的后向预报模式发现，NPIW面积调制是由北太平洋中部阿留申低压活动的第一模斜压海洋响应引起的。

The North Pacific Intermediate Water (NPIW), which is characterized as a vertical salinity minimum layer, is distributed at a depth of 200-1000m. In this study, we investigated temporal features of NPIW area by using the repeat hydrographic section along 137E meridian conducted by the Japan Meteorological Agency from 1972 to 2008. Variations of NPIW area showed a clear quasi-decadal (about 10 years)modulation. By using a wind-driven hindcast model, it was found that the NPIW area modulation was caused by the first-mode baroclinic ocean response to the Aleutian Low activities located in the central North Pacific.