Journal of Oceanography, Vol. 56 (No. 3), pp. 331-344, 2000
Akihiko Morimoto1*, Koichi Yoshimoto1 and Tetsuo Yanagi2
1Department of Civil and Environmental Engineering, Ehime University,
Matsuyama 790-8577, Japan
2Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
(Received 20 May 1999; in revised form 14 September 1999; accepted 21 October 1999)
Abstract: Temporal and spatial variations of sea surface circulation in the South China Sea were revealed with use of altimetric data provided by TOPEX/POSEIDON from December 1992 to October 1997. The estimated distribution of sea surface dynamic heights from altimetric data coincide well with the results of observation by Soong et al. (1995) and Chu et al. (1998). The RMS variability of sea surface dynamic height, which is obtained after tidal correction based on Yanagi et al. (1997), is high in the central part of the South China Sea, the Gulf of Tongking, the Sunda Shelf and the Gulf of Thailand. The high RMS variability in the Gulf of Tongking, the Sunda Shelf and the Gulf of Thailand is due to set up and set down of sea water by the East Asian monsoon, which is northeasterly during winter and southwesterly during summer. Also, the high RMS variability in the central part of the South China Sea is due to the variations of basin-wide circulation. The circulations are dominant in the central part of the South China Sea during summer and winter, an anticyclonic circulation during summer and a cyclonic circulation during winter. It is suggested that these circulations are controlled by the East Asian monsoon. Hence, there is an interannual variability of the basin-wide circulation associated with the variation of the East Asian monsoon.