LARGE-SCALE SEA-LEVEL, THERMOCLINE, AND WIND VARIATIONS IN THE INDONESIAN THROUGHFLOW REGION

The Indonesian throughflow is presumed to be driven by a sea level gra dient from the Pacific to the Indian Ocean. Deep throughflow transport may also be driven by a steric gradient between the two basins. The s ell level gradient, in turn, is thought to be maintained by the differ ing wind patterns in the two basins: monsoonal in the Indian Ocean and trades in the western equatorial Pacific. In the interaction between sea level, wind stress, and thermocline depth as identified from histo rical measurements, we find (1) over the Indian, Indonesian, and equat orial Pacific basins and specifically within the throughflow region, s ea level and thermocline seasonal variations are negatively correlated (sea level rise corresponding to thermocline deepening) and sea level and meridional wind stress are also correlated; (2) the expected stro ng seasonal gradients in sea level through the eastern throughflow reg ion (near the island of Timer) are found, though without an accompanyi ng thermocline depth gradient; (3) seasonal convergence in baroclinic, upper ocean throughflow transport previously identified [Meyers et al ., 1995] in the Timor Sea is associated with changes in sea level as w ell as upper ocean dynamic height at annual period but not at semiannu al; (4) interannual variability explains more of the sea level varianc e in the eastern throughflow region than is explained by seasonal harm onics; however, there does not appear to be a strong interannual signa l in the sea level gradient to drive fluctuations in the upper ocean t hroughflow. We hypothesize that seasonal variability in the upper laye r throughflow and interannual variability in the deep throughflow are the predominant results of the complex interaction of forcing mechanis ms.