The Kuroshio east of Taiwan: Moored transport observations from the WOCE PCM-1 array

Observations from the WOCE PCM-1 moored current meter array east of Taiwan for the period September 1994 to May 1996 are used to derive estimates of t he Kuroshio transport at the entrance to the East China Sea. Three differen t methods of calculating the Kuroshio transport are employed and compared. These methods include 1) a "direct'' method that uses conventional interpol ation of the measured currents and extrapolation to the surface and bottom to estimate the current structure, 2) a "dynamic height'' method in which m oored temperature measurements from moorings on opposite sides of the chann el are used to estimate dynamic height differences across the current and s patially averaged baroclinic transport profiles, and 3) an "adjusted geostr ophic'' method in which all moored temperature measurements within the arra y are used to estimate a relative geostrophic velocity field that is refere nced and adjusted by the available direct current measurements. The first t wo methods are largely independent and are shown to produce very similar tr ansport results. The latter two methods are particularly useful in situatio ns where direct current measurements may have marginal resolution for accur ate transport estimates. These methods should be generally applicable in ot her settings and illustrate the benefits of including a dynamic height meas uring capability as a backup for conventional direct transport calculations . The mean transport of the Kuroshio over the 20-month duration of the expe riment ranges from 20.7 to 22.1 Sv (1 Sv = 10(6) m(3) s(-1)) for the three methods, or within 1.3 Sv of each other. The overall mean transport for the Kuroshio is estimated to be 21.5 Sv with an uncertainty of 2.5 Sv. All met hods show a similar range of variability of +/-10 Sv with dominant timescal es of several months. Fluctuations in the transport are shown to have a rob ust vertical structure, with over 90% of the transport variance explained b y a single vertical mode. The moored transports are used to determine the r elationship between Kuroshio transport and sea-level difference between Tai wan and the southern Ryukyu Islands, allowing for long-term monitoring of t he Kuroshio inflow to the East China Sea.