Origins of the Indonesian Throughflow Controlled by the Mindanao Current Strength : Simple Model Study
Toru Miyama*1, Bo Qiu*2 and Toshiyuki Awaji*3
*1 International Pacific Research Center, the University of Hawaii
*2 Department of Oceanography, the University of Hawaii
*3 Department of Geophysics, Kyoto University
Dependence of the Indonesian Throughflow upon the strength of the Mindanao Current was investigated using a simple reduced-gravity model. The strength of the Mindanao Current was controlled by the various steady wind stress curl in the North Pacific Ocean in this study.
The horizontal resolution of the model was 1/4 degree in longitude and latitude.
The average total transport of the Indonesian Throughflow was found to be hardly affected by the wind strength in the northern hemisphere, which supports Godfrey's [1989] island rule. However, the transport through each strait depended on the wind stress curl in the northern hemisphere or the strength of the Mindanao Current. As the Mindanao Current strengthened, the water from the Mindanao Current increased in the Indonesian Throughflow passing through the Makassar Strait.
The Indonesian Throughflow oscillated with a period about 40 days in some parameter range. This oscillation was due to the eddy detachment from the Mindanao Eddy. Analysis using constant absolute vorticity trajectories showed that this oscillation tended to happen with 70cm/s ＜ Vc ＜ 160cm/s where Vc was the velocity of the Mindanao Current at the southeastern coast of the Mindanao Island. The result in this study suggested that the Mindanao Current is likely to shed eddies under the realistic wind strength. Kashino et al. [1998] reported the current oscillation with similar time scale in the JAMSTEC observation. This might be precious evidence of the eddy activity in the Mindanao current system.
