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Patterns of upper layer circulation variability in the South China Sea from satellite altimetry using the self-organizing map
Acta Oceanologica Sinica (2008)
  • Yonggang Liu, University of South Florida
  • Robert H Weisberg, University of South Florida
  • Yaochu Yuan
Abstract

Patterns of the South China Sea (SCS) circulation variability are extracted from merged satellite altimetry data from October 1992 through August 2004 by using the self-organizing map (SOM). The annual cycle, seasonal and inter-annual variations of the SCS surface circulation are identified through the evolution of the characteristic circulation patterns. The annual cycle of the SCS gener- al circulation patterns is described as a change between two opposite basin-scale SW-NE oriented gyres embedded with eddies: low sea surface height anomaly (SSHA) (cyclonic) in winter and high SSHA (anticyclonic) in summer half year. The transition starts from July--August (January--February) with a high (low) SSHA tongue east of Vietnam around 12°~14° N, which de- velopa into a big anticyclonic (cyclonic) gyre while moving eastward to the deep basin. During the transitions, a dipole structure, cyclonic (anticyclonic) in the north and anticyclonic (cyclonic) in the south, may be formed southeast off Vietnam with a strong zonal jet around 10°~12° N. The seasonal variation is modulated by the interannual variations. Besides the strong 1997/1998 e- vent in response to the peak Pacific El Nino in 1997, the overall SCS sea level is found to have a significant rise during 1999~ 2001, however, in summer 2004 the overall SCS sea level is lower and the basin-wide anticyclonic gyre becomes weaker than the other years.

Publication Date
2008
Citation Information
Yonggang Liu, Robert H Weisberg and Yaochu Yuan. "Patterns of upper layer circulation variability in the South China Sea from satellite altimetry using the self-organizing map" Acta Oceanologica Sinica Vol. 27 Iss. Suppl (2008)
Available at: http://works.bepress.com/yliu/15/