Satellite altimeter monitoring the Kuroshio Transport south of Japan



In 1993–1995, we carried out observations of the Kuroshio south of Japan, including direct current measurements and repeated hydrographic surveys along a satellite track of the TOPEX/POSEIDON altimeter. The velocity field of the Kuroshio is determined by geostrophic calculation using the repeated hydrographic survey data, referenced to velocities observed at mid and abyssal depths. The volume transport of the Kuroshio is estimated from this velocity field. The estimated transports of the Kuroshio have a high correlation with sea-surface height differences across the Kuroshio. Having this relationship and using the altimeter data, we obtained a time series of the Kuroshio transport over seven years at ten-day intervals. The Kuroshio transport, excluding contributions by local recirculations, is estimated to be 42 × 106 m³/sec on average. The correlation between sea-surface height difference and transport provides a practical method of long-term monitoring of the Kuroshio transport using satellite altimetry.