| Oyashio water flowing into the Mixed Water Region (MWR) and the KuroshioExtension region that forms North Pacific Intermediate Water (NPIW) wasexamined, based on four CTD/L-ADCP surveys of water masses and oceancurrents.There are two processes for the Oyashio water intrusion across thesubarctic front (SAF): One is the direct cross-nearshore-SAF transportnear Hokkaido along the western boundery, and the other is thecross-offshore-SAF process probably due to isopycnal mixing.Seasonal variations were observed in the former process, and thetransport of the Oyashio water across SAF near Hokkaido in thedensity range of 26.6-27.4σθ was 5-10Sv in spring 1998and 2001, and 0-4Sv in autumn 2000, mainly corresponding to the changeof the southwestward Oyashio transport.Through the latter process, about 6Sv of the Oyashio water was entrainedacross the offshore SAF from off Hokkaido to 150°E in bothspring 2001 and autumn 2000.The total cross-SAF Oyashio water transport contributing to NPIWformation is more than 10Sv that is larger than the ones reportedpreviously.Most of the Oyashio water through the former process were transportedsoutheastward through the Kuroshio Extension.The Oyashio intrusion through the latter process is suggested to feedNPIW in the northern part of the MWR, mainly along the subarcticboundary/SAF. |
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