The NPTW is characterized by a salinity maximum of or Practical Salinity Units which is relatively high. As the water mass is advected southward by the MC, it evolves: the salinity maximum decays by along the Philippine coast. Once it reaches a latitude of 6°N, it becomes indiscernible. In contrast, the waters of the MUC transport Antarctic Intermediate Water which originates from the south Pacific. It is characterized by a salinity greater than and usually contains more oxygen than the NPIW.

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