[1] More than 6 years of satellite-derived ocean color (SeaWiFS) and 7 years of sea surface temperature (AVHRR) and sea surface wind (ERS1/2, NSCAT, and QuikSCAT) are investigated for the Indonesian Seas. Harmonic analysis and monthly means in ocean color indicate that during the southeast AsiaAustralia monsoon southeasterly wind from Australia generates upwelling and brings cooler and nutrientrich water near the surface, enhancing productivity and increasing ocean color in the Banda Sea and the southern coasts of Jawa (Java)-Sumatra. Conditions are reversed during the northwest monsoon. The northwest wind induces downwelling and produces a weaker biological response in terms of ocean color. Anomalous winds associated with the 1997-1998 El Niño/La Niña events coinciding with the Indian Ocean Dipole (IOD) produced significant departures from the 6-year monthly mean in both magnitude and timing of the seasonal response to the southeast monsoon. Ocean color intensified in the upwelling region along the southern coast of Jawa-Sumatra, and the area of increased amplitude extended westward and prolonged the southeast monsoon period. In addition, localized minimum values of ocean color are observed along the exit pathways of the Indonesian Throughflow.

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[1] Unlike most eastern boundary currents, the Leeuwin Current off the west coast of Australia flows poleward and is therefore warm, nutrient-poor and suppresses upwelling. As a result, the waters off Western Australia are relatively oligotrophic. Primary productivity and concentrations of chlorophyll are particularly low in summer, when the water column is stratified and most chlorophyll is concentrated in a layer above the nutricline at approximately 100 m depth. The phytoplankton blooms in late autumn and winter, coinciding with the period of strongest Leeuwin flow. The bloom in winter is maintained by cooling and storms, which promote convective mixing of the upper water column and a shoaling of the nutricline and chlorophyll maximum layer. However, the late autumn bloom coincides with the initial intensification of the Leeuwin Current. Eddies and meanders spin up just beyond the shelf break, and Leeuwin Current water was observed at this time to destratify the water column and flood the shelf with relatively nutrient-rich water. Several potential sources for the nutrients are proposed: upwelling by the eddies and meanders as they induce cross-shelf motions; advection from the north, where the nutricline is shallower; and seasonal cooling.

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