The circulation patterns of the Asian summer and winter monsoons dominate the seasonal patterns of winds, precipitation, and runoff and determine, in part, the character of land vegetation over southern and eastern Asia (Hastenrath, 1991; Hastenrath and Greischar, 1993; Webster, 1987; Webster, 1994; Webster et al., 1998, Lau and Yang, 1997). The winter monsoon is characterized by continental cooling and development of high pressure over northern Asia, northeast winds across the South China Sea (which intensify during cold surges), and increased rainfall in the Austral-Asian equatorial zone (Fig. 1A, 1C). Similarly, northwest winds are found in the Indian Ocean, although they are not accompanied by cold surges. The summer monsoon circulation is characterized by continental heating, the development of low pressure over Tibet, and southerly winds across all of southern Asia. In the South China Sea, the summer monsoon is marked by moderate (5 m/s) southerly winds, weak to moderate upwelling off Vietnam, and high precipitation over southern and eastern Asia (Fig. 1B, 1D). In contrast, the summer monsoon exhibits strong (10 m/s) southwesterly winds and intense upwelling in the Arabian Sea. The location of the South China Sea between East Asia and the maritime continent is ideal to record the paleoceanographic responses to both winter and summer monsoons (Figs. 1, 2).
Tectonic Framework of the South China Sea
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