CSIRO Marine and Atmospheric Research
Past Seminars

Friday, 3 October 2003 at 11.30 am (Tas time)

CSIRO Auditorium, Hobart and via videoconference to Floreat and Cleveland

Susan Wijffels and Gary Meyers
CSIRO Marine Research

Fifteen years of XBT measurements in the Indonesian throughflow

In the early 1980s, a network of frequently repeated eXendable BathyThermograph (XBT) sections were established in the eastern South Indian Ocean as part of the Tropical Ocean Global Atmosphere experiment. Nearly twenty years later these lines are still operating and are shedding light on the mean structure of the Indonesian Throughflow and its interannual variability. In particular, seasonal anomalies of subsurface temperature variability in the Throughflow region can be seen as largely due to the interaction of remotely wind driven waves originating along the Indian and Pacific Ocean equators. Transport variability is less easily understood. The barotropic Island Rule cannot account for the observed baroclinic transport changes. Mean transports relative to 800m are near 9Sv (geostrophic plus Ekman), with the Throughflow characterized by a subsurface velocity maximum near 100m. Comparisons with moored transport estimates shed light on the less well known flow at and below 700m, the depth reached by the XBTs. Combining the information from the XBT data and mooring data we revisit the effect of the Throughflow on the Pacific basin-wide heat and freshwater divergences.

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