Water mass analyses revealed larger negative salinity anomalies ( 15 μmol kg ⁻¹ ) than those of the surrounding water.
Small water parcels, which are characterized by a low salinity and high dissolved oxygen (DO) are observed by Seaglider in the main thermocline (26.0–27.0 σ θ ) south of the Kuroshio Extension (KE), have horizontal and vertical scales of a few tens of kilometers and a few tens of meters, respectively. For the upper-type Kiddies, they are probably generated through subduction associated with mixed-layer frontogenesis, which at least contribute to 0.25 Sv annual subduction rate for the layers 26.2–26.7 sig0. Water property analysis suggests that the Kiddies most likely originate from the SAF region. Based on STEs' spatial distributions and vertical locations, we propose to name these STEs as KE intermediate-layer eddies (Kiddies). Spatially, the STEs are primarily distributed within the region between the Kuroshio Extension (KE) and subarctic front (SAF) in meridional and 140–155˚E in zonal direction. The number of upper-type STEs is much larger in spring and summer than in autumn and winter while that of lower-type ones show relatively uniform seasonal distributions. According to their different densities and seasonalities, the STEs are classified into upper and lower types with density interface of 26.7 sig0. Vertical and horizontal scale of the STEs is generally between 100–200 m and 5–15 km, respectively, suggesting that they are in the category of submesoscale processes.
The STEs' cores are located between 26.2–27.0 sig0 and their shapes share a uniform Gaussian structure in vertical. By applying an objective identification procedure to Argo T/S profiles, a total of 337 lens-like STEs that trap cold and fresh homogeneous water are obtained. in the northwestern Pacific are further investigated with 14-year Argo temperature/salinity (T/S) data between 2002–2015. In this study, statistical characteristics of the cold-core subthermocline eddies (STEs) discovered by Zhang et al.
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