Regulation of South China Sea Throughflow by Pressure difference due to Thermohaline and Wind-driven circulations

Huiling Qin, South China Sea Institute of Oceanology (SCSIO), Chinese Academy of Science, Guangzhou,, China, Rui Xin Huang, Woods Hole Oceanographic Institution, Department of Physical Oceanography,, MA, United States, Huijie Xue, University of Maine, Orono, ME, United States and Weiqiang Wang, South China Sea Institute of Oceanology, Chinese Academy of Sciences, State Key Laboratory of Tropical Oceanography, Guangzhou 510301, China
Abstract:
Sea surface height data from Simple Ocean Data Assimilation dataset are used to determine the pressure difference relative to variability of the South China Sea ThroughFlow (SCSTF) from 1958 to 2007. Two branches of SCSTF, that is Karimata Strait ThroughFlow (KSTF) and Mindoro Strait ThroughFlow (MSTF), are examined.

Using ensemble empirical mode decomposition method, time series of pressure difference and volume transport have been decomposed into intrinsic mode functions, which indicate their variability on different time scales. Pressure difference, mainly decided by the SSH east of the Luzon Strait, agrees with KSTF volume transport on decadal time scale; while for MSTF, pressure difference varies similarly with volume transport on interannual time scale. Separating into the thermosteric and halosteric terms, for KSTF approximately two-thirds of the steric sea level difference (30 cm) is due to the thermosteric contributions; while the remaining one-third of steric sea level difference (14 cm) is due to the halosteric contributions. For MSTF, the steric sea level difference is due primarily to the thermosteric difference.

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