Observed Tidal Currents and the Characteristics of Principal Tidal Constituents in the South China Sea Deep Basin in 1997-1999

摘要

Current observations from three moored Autonomous TemperaturernLine Acquisition System (ATLAS) buoys are analyzed to examine therntidal currents in the upper layer of central deep basin of South ChinarnSea (SCS). Spectrum analysis of current data shows that diurnal andrnsemi-diurnal tidal constituents play an important role in the total current,rnespecially the diurnal tidal constituents. In the northern SCS deep basin,rntwo major diurnal constituents K_1 and O_1 could contribute 33% andrn21% to depth averaged current, respectively. From north to south, thernmagnitude of diurnal tidal constituents to the total current decreasernwhile that of semi-diurnal tidal constituents remain similar. Thernmagnitude, direction and contribution of most tidal currents, except thernsemi-diurnal tidal current in the northern part, vary significantly withrnwater depth. This indicates that the tidal current is mainly baroclinic inrnupper layer of SCS deep basin.