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Lagrangian data from 657 SVP drifters, CNES/Aviso (Archiving, Validation, and Interpretation of Satellite Oceanographic data) time variable satellite altimeter sea level anomaly and Levitus 98 hydrographic data are used to develop 0.25° spatial resolution maps of the mean and eddy circulations in the northwestern Pacific during the 1990s. Drifter velocities at 15 m depth and 200 m temperature data clearly indicate in the Kuroshio Extension (KE) jet two prominent meanders that culminate in a 300 km northward deflection east of the Shatsky Rise at 160°E. The interannual trends of Aviso mesoscale variance are absent along the path of the meandering KE jet. Three anticyclonic recirculations can be identified south or southeast of the Kuroshio, the southernmost around Daito Island being a new discovery. About 3% of the drifters with drogues attached crossed the Kuroshio front. The Aviso currents are correlated at 0.8 with drifter geostrophic velocity. The Aviso geostrophic currents are adjusted in amplitude to the contemporaneous drifter observations and are further used to compute an unbiased mean geostrophic circulation and the quasi‐geostrophic Reynolds' stresses in the KE region. The principal axes of the eddy Reynolds' stresses are oriented along the unbiased mean velocity vectors within the meandering KE jet. The time‐mean horizontal momentum balance that includes both the mean and eddy momentum convergences is used to compute absolute sea level map and its uncertainty. At 145°E the 2000 m depth absolute dynamic height referenced to the sea level reveals a heretofore unknown 70 dynamic cm drop from 25° to 42°N.
Niiler et al. (Sun,) studied this question.