A dynamical analysis of the Indonesian seas throughflow

William Howell Burnett


A barotropic, non-linear, high-resolution model (Princeton Ocean Model) centered over the Indonesian Seas is used to investigate the fundamental dynamics of the Indonesian Seas throughflow. The model is initially prescribed with a seasonally varying transport through four open ports, with and without monthly wind forcing. The model is also configured such that sea-surface elevations are prescribed, and not the transport. The model's horizontal circulation patterns show that the throughflow enters the Makassar Strait, the Malucca Sea, and the Halmahera Sea and exits via the Lombok, Sumba, Ombai, Straits and the Timor Sea. Local wind forcing causes the majority of the Mindanao Current transport to flow to the east during the southeast monsoon, and flow towards the Celebes Sea during the northwest monsoon. The geostrophic approximation is applicable over a majority of the model domain and at the four open ports except at the equator, where the Coriolis acceleration vanishes, in which case the horizontal momentum diffusion and momentum advection balance the pressure gradient term. An analysis of the energy equation shows that the work of the pressure forces at the open ports is balanced by the work of horizontal frictional forces and the work of bottom friction over the model domain. Model results show that the resultant of the pressure forces acting on the bottom (the bottom form stress) is important in the dynamics of the Indonesian Seas throughflow. These results lend credence to the hypothesis that the pressure head between the Pacific and Indian Ocean does not significantly influence the Indonesian throughflow in cases of variable topography.