ADVECTION AND DIFFUSION OF INDONESIAN THROUGHFLOW WATER WITHIN THE INDIAN-OCEAN SOUTH EQUATORIAL CURRENT

Warm, low salinity Pacific water weaves through the Indonesian Seas in to the eastern boundary of the Indian Ocean. The Indonesian Throughflo w Water (ITW) adds freshwater into the Indian Ocean as it spreads by t he advection and diffusion within the Indian Ocean's South Equatorial Current (SEC). The low salinity throughflow trace, centered along 12 d egrees S, stretches across the Indian Ocean, separating the monsoon do minated regime of the northern Indian Ocean from the more typical subt ropical stratification to the south. ITW is well represented within th e SEC thermocline, extending with concentrations above 80% of initial characteristics from the sea surface to 300-m within the eastern half of the Indian Ocean, with 60% concentration reaching well into the wes tern Indian Ocean. The ITW transport within the SEC varies from 4 to 1 2 x 10(6) m(3)sec(-1), partly in response to variations of the injecti on rate at the eastern boundary and to the likelihood of a zonally elo ngated recirculation cell between the Equatorial Counter Current and t he SEC within the Indian Ocean. Lateral mixing disperses the ITW plume meridionally with an effective isopycnal mixing coefficient of 1.1 to 1.6 x 10(4) m(2)sec(-1).