Shallow throughflow variability in the outflow straits of Indonesia

Since December 1995, the Indonesian throughflow has been monitored in five major passages as it flows from the Indonesian interior seas to the Indian Ocean. Pressure differences across the straits enable us to infer the geost rophic surface flow, : and so provide the first simultaneous time-series me asurements of surface geostrophic flow through these passages. Intraseasona l signals (30-90 day) are a ubiquitous feature in the surface flow, and are consistent with wind-forced Kelvin waves from both the eastern equatorial Indian Ocean and the south coast of Java. Using a relationship with surface velocity from three contemporaneous ADCP surveys, we approximate surface ( 0-100 m) volume transport fluctuations through four of the main exit passag es. The amplitude of the total surface transport variation through these pa ssages is fairly uniform, ranging from 10-15 Sv.