Intraseasonal Kelvin Waves in the Indonesian Throughflow Passages

Time series observations during 2004-2006 reveal the presence of 60-90 days intraseasonal events that impact the transport and mixing environment within Makassar Strait, the main inflow passage of the Indonesian Throughflow. The observed velocity and temperature fluctuations within the pycnocline reveal the presence of Kelvin waves including vertical energy propagation, energy equipartition, and non-dispersive relationship. Two current meters at 750 m and 1500 m provide further evidence that the vertical structure of the downwelling Kelvin wave resembles that of the second baroclinic wave mode. The Kelvin waves derive their energy from the equatorial Indian Ocean winds, including those associated with the Madden-Julian Oscillations, and propagate from Lombok Strait to Makassar Strait along the 100-m isobath. The northward propagating Kelvin Waves within the pycnocline reduce the southward Makassar Strait throughflow by up to 2 Sv and induce a vertical mixing rate of 1-5x10-5 m2s-1