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 Temperature Line Acquisition System (ATLAS) buoys are analyzed to examine the tidal currents in the upper layer of central deep basin of South China Sea (SCS). Spectrum analysis of current data shows that diurnal and semi-diurnal tidal constituents play an important role in the total current, especially the diurnal tidal constituents. In the northern SCS deep basin, two major diurnal constituents K_1 and O_1 could contribute 33% and 21% to depth averaged current, respectively. From north to south, the magnitude of diurnal tidal constituents to the total current decrease while that of semi-diurnal tidal constituents remain similar. The magnitude, direction and contribution of most tidal currents, except the semi-diurnal tidal current in the northern part, vary significantly with water depth. This indicates that the tidal current is mainly baroclinic in upper layer of SCS deep basin.