Seasonal Variations of Tidal and Residual Currents Near the Pearl River Estuary

Abstract

Quantifying the currents near the Pearl River Estuary is vital for understanding the circulation in the South China Sea. Based on the observational data of currents near the Pearl River Estuary from September 2017 to August 2018, the seasonal variations of tidal currents and residual currents at this point are analyzed. The results show that the tidal and current types in the west side of the Pearl River Estuary are irregular semidiurnal tides and irregular semidiurnal tidal currents. The diurnal O1 and K1 tide components show the characteristics of rotational flow. The half-day tidal component M2 and S2 are reciprocating. Ssa tidal component also contributes significantly. The residual current in the observed sea area is strong in autumn and winter, weak in spring and summer, strong in surface layer and weak in bottom layer, and the flow direction keeps southwest almost all year round. Especially during the southwest monsoon period in summer, the current along the west of the Pearl River Estuary presents the characteristics of adverse wind, and its velocity is about 10 cm/s.