ABSTRACT
The South China Sea (SCS), the largest marginal sea in Southeast Asia, is influenced by the seasonal East Asia Monsoon. In the northern hemisphere winter, winds flow from the northeast over the SCS. In marked contrast, during the northern hemisphere summer, winds are from the southwest, driven by low pressure over mainland Asia and high pressure over Australia, and are considerably weaker. The reversal initiates considerable changes in the current systems of the SCS and dominates wave directions. Internal waves can impact the north part of the SCS, and tides with ranges in excess of 1.5 across the area generate complex currents. The 51 atolls in this area are most commonly semi-closed, with several submerged, and progressively more being anthropogenically modified. In the more northerly region, the Paracel Islands are nine atolls, most of which form on bathymetric highs on the continental shelf and slope off Vietnam and China. Scarborough Atoll to the east is the exception, forming on a seamount. The Spratly Archipelago, offshore of Borneo, contains the majority of the atolls in the SCS. Nine of these are found on the continental slope, while the remaining 33 are found capping seamounts. In addition, we document four atolls in the adjacent Sulu Sea.
