Sea-level trend in the South China Sea observed from 20 years of along-track satellite altimetric data

Abstract

The sea-level trend in the South China Sea (SCS) is investigated based on 20 years of along-track data from TOPEX and Jason–1/2 satellite altimetry. The average sea-level rise over all the regions in the study area is observed to have a rate of 5.1 ± 0.8 mm year⁻¹ for the period from 1993 to 2012. The steric sea level contributes 45% to the observed sea-level trend. These results are consistent with previous studies. In addition, the results demonstrate that the maximum sea-level rise rate of 8.4 mm year^–1 is occurring off the east coast of Vietnam and eastern part of SCS. During 2010–2011, the La Niña event was highly correlated with the dramatic sea-level rise in the SCS; La Niña events were also associated with the maximum rate of sea rise off the east coast of Vietnam, which occurred during 1993 and 2012. We also evaluated the trends in the geophysical (e.g. dynamical atmospheric correction (DAC)) and range corrections (e.g. wet tropospheric correction, dry tropospheric correction, and ionosphere correction), which can leak into the observed sea-level record and be interpreted as part of the sea-level trend. The mean DAC trend within the SCS is found to be 0.4 ± 0.1 mm year^–1 with >0.7 mm year^–1 exhibited in the northern portion of the SCS. This is validated by comparing the altimetric data with the DAC-corrected tide gauge data at Xisha. In the southern SCS, the trend in wet troposphere correction, which is based on radiometer measurements on board the satellite, should be considered for local sea-level trend estimation.

Acknowledgement

We thank RADS (Radar Altimeter Database System) for providing altimetric data.

Funding

This study was supported by the project ‘MyOcean2’, which is granted by the European Commission within the GMES Programme (7th Framework Programme); the National Natural Science Foundation of China [grants numbers 41306194 and 41006108]; the Open Fund of State Key Laboratory of Tropical Oceanography; the South China Sea Institute of Oceanology; Chinese Academy of Sciences [grant number LTO1108].