Velocity and transport structure of the Kuroshio Extension at 35°N, 152°E

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Abstract
A current meter mooring maintained for 2 years at 35°N, 152°E as part of the “Wespac” array (Schmitz et al., 1987) sampled the Kuroshio Extension during the last 390 days of deployment. Based on a method developed by Hall and Bryden (1985) for the Gulf Stream at 68°W, velocity and temperature time series at five depths from 350 to 6000 m have been used to construct the representative horizontal velocity structure of the current. Cross‐stream position is quantified in terms of temperature at 350 dbar, and an alongstream flow direction is defined on the basis of the current shear. Integrated transport of the Kuroshio is 87±21 Sv, compared to 94±26 Sv for the Gulf Stream at 68°W based on analogous data sets and analysis techniques. The two currents are compared in terms of horizontal and vertical distributions of transport as well as relative strength of barotropic and baroclinic components. The Kuroshio has a larger relative barotropic component than the Gulf Stream, while the latter has a stronger, deeper thermocline expression. The effects of rotating velocity measurements to a continuously changing alongstream direction are examined for both currents; the major impact is to cut the apparent velocity variance in half, demonstrating that much of the original variance is due to the meandering of a quasi‐fixed velocity profile rather than the passage of eddies. Results from these somewhat unconventional analysis methods are placed in broader geographical context and compare favorably with more traditional methods of determining these currents' transports.

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