Kuroshio Transports

Kuroshio volume and temperature transports were calculated using the daily velocity sections that were presented in Kuroshio Velocities section. We used these time series to investigate the relationship between Kuroshio meanders and transports. To accomplish this goal, a quantitative measure of Kuroshio offshore position was needed.

The position of the Kuroshio off southwestern Japan can be estimated by the location of the 15°C isotherm at 300 m (Tomczak and Godfrey 1994). The GEM T section time series was used to calculate a time series of Kuroshio position along the ASUKA line using this definition.

For 77% of the time, Kuroshio position was within 80 km of Cape Ashizuri. In this no-meander state, mean position appears to have shifted gradually 10 km to the south during the two-year field study. The other 23% of the time consisted of three big and three little meanders. The big meanders were excursions beyond 140 km from the Cape, each one lasting two months. The little meanders were excursions beyond 80 km from the Cape, each lasting several days. Time spacing between the six meander maxima varied from 102 to 137 days and its average was 123 days. This calculation quantifies the observations from Dynamic Heights section, where meanders were observed in the dynamic height field in the months of February, June, and October. A seven-year time-series measurement of Kuroshio position off Cape Ashizuri showed a similar pattern (Wimbush et al. 1998), with meanders occurring in January/February, May/June, and September/October rather than other months. This suggests a three-cycle-per-year phenomenon, phase-locked to the annual cycle.

NEXT: Transports continued

Abstract

Introduction

Dynamic Heights

Velocities

Transports

Conclusions

References

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