Identification of Tidal Current Vertical Structure in Ombai Strait and Timor Passage

Abstract

Indonesian seas are strongly affected by strong semidiurnal tidal signals from the Indian Ocean and diurnal signals from the Pacific Ocean. Therefore, within the internal seas, there is possibility of mixed tides (semidiurnal and diurnal signals). This research is focused on determining tidal current based on the velocity data measured during the INSTANT (International Nusantara Stratification and Transport) program. The velocity data from Ombai Strait and Timor Passage from January 18, 2004 to December 31, 2004 are analyzed. Characteristics of tidal current data at certain fixed depths (50, 100, 350 and 750 meters) are processed and calculated using MATLAB software and present the magnitude and variability of total currents, residual currents, and tidal currents as well as vertical variability at these straits. In Ombai Strait and Timor Passage currents tend to move zonally (east – west). The dominant tidal currents are observed at 350 and 750 meters, while subtidal (nontidal) current dominant occurs with 50 to 150 meters.