On steric and mass-induced contributions to the annual sea-level variations in the South China Sea

The steric sea level (SLA(steric)), water-mass change (SLA(mass)) and their contributions to the sea level anomaly (SLA) in the South China Sea (SCS) are studied by using altimetry data, Ishii data and GRACE data. Annual harmonic results and correlation analysis indicate that the SLA(steric) has a significant contribution to the SLA over deep basin and that its phase leads SLA 1-3 months in different parts of the SCS, whereas the SLA(mass) explains the SLA to a great extent over shallow water areas. The area-averaged SLA in the western SCS has an amplitude of similar to 7.6 cm and a phase of similar to 360 degrees, which is similar to 3.8 cm higher and peaks similar to 108 degrees later than SLA(steric). The SLA(mass) has an amplitude of similar to 6.3 cm and a phase of similar to 337 degrees. The simultaneous correlation coefficient between SLA and SLA(mass) is 0.78, which indicates that mass variation dominates the sea-level variation in the western SCS. Unlike the western SCS, the area-averaged SLA in the central SCS peaks at 254 degrees with a smaller amplitude of similar to 3.3 cm, which is similar to 1.8 cm lower and peaks similar to 15 days later than corresponding SLA(steric). The simultaneous correlation coefficient between SLA and SLA(steric) is 0.81; therefore, the contribution of steric variation to the sea-level variation is dominant in the central SCS. (C) 2010 Elsevier B.V. All rights reserved.