Mean transport and seasonal cycle of the Kuroshio east of Taiwan with comparison to the Florida Current

Moored observations of Kuroshio current structure and transport variability were made across the channel between northeast Taiwan and the Ryukyu Islan ds at 24 degreesN from September 19, 1994, to May 27, 1996. This was a coop erative, effort between the United States and Taiwan. The moored array was designated PCM-1, for the World Ocean Circulation Experiment (WOCE) transpo rt resolving array. The dominant current and transport variability occurred on 100-day timescales and is shown by Zhang et al. [2001] to be caused by warm mesoscale eddys merging with the Kuroshio south of the array causing o ffshore meandering and flow splitting around the Ryukyu Islands. An annual transport cycle could not be resolved from our 20-month moored record becau se of abasing from the 100-day period events. Sea level difference data wer e used to extend the transport time series to 7 years giving a variation in the range of the annual transport cycle of 4-10 Sv, with a mean range clos er to 4 Sv. The seasonal maximum of 24 Sv occurred in the summer and the se asonal minimum of 20 Sv occurred in the fall. A weaker secondary maximum al so occurred in the winter. The cycle of Kuroshio transport appears to resul t from a combination of local along-channel wind forcing and Sverdrup forci ng over the Philippine Sea. Our estimate of the mean transport of the Kuros hio at the entrance to the East China Sea from the moored array is 21.5 +/- 2.5 Sv. The mean transpacific balance of meridional flows forced by winds and thermohaline processes at this latitude requires an additional mean nor thward flow of 12 Sv with an annual cycle of +/-8 Sv along the eastern boun dary of the Ryukyu Islands. The mean transport and annual cycle of the Kuro shio were found to be in reasonable agreement with basin-scale wind-forced models. Remarkable similarities are shown to exist between the mean western boundary currents and their seasonal cycles in the Atlantic (Florida Curre nt and Antilles Current) and Pacific (Kuroshio and boundary current east of Ryukyu Island chain) at the same latitude. However, detailed comparison sh ows that the mean Kuroshio is weaker and more surface intensified than the mean Florida Current, while the Kuroshio-transport variability is significa ntly larger.