An Examination of Seasonal Mean Circulation and Salinity Distributions in the Pearl River Estuary of China Using a Nested-Grid Coastal Ocean Circulation Model

A three-level nested-grid coastal ocean modeling system was developed recently by Tang et al. (2009) for the Pearl River Estuary (PRE) in South China's Guangdong Province. The modeling system has three downscaling subcomponents: (a) a coarse-resolution outer model for China Seas from Bohai Sea to the northern South China Sea; (b) an intermediate-resolution middle model for coastal waters over the northern shelf of South China Sea; and (c) a fine-resolution inner model for the PRE and adjacent waters. The modeling system is forced by tides, meteorological forcing and buoyancy forcing associated with freshwater runoff from the Pearl River system. Multi-year model results in 1993–95 are used in this study in examining circulation and salinity distributions during the dry (December–March) and wet (May–August) seasons in the PRE. The seasonal mean circulation and salinity distributions in the dry season are affected significantly by freshwater runoff, wind and tides over the northern and western PRE and mainly by wind and tidal forcing over the outer PRE and adjacent inner shelf waters. In the wet season, the estuarine plume extends significantly offshore with river discharge and tides to be the main driving for circulation and salinity distributions inside the PRE, and tides and wind forcing to be the main driving forcing over the inner shelf waters off the PRE.