Objectives Coastal sea level rise poses direct threats to human livelihood. It is of scientific importance to understand the causes and provide useful strategies for adapting sea level rise. This paper aims to investigate the causes of coastal sea level change using satellite altimetry, satellite time-variable gravity, and Argo floats.
Methods Given that time-variable gravity suffers from serious leakage issue over coastal area, we use land mass variations from a mascon solution to simulate the leakage from land into oceans, which is estimated to be 0.68 mm/a.
Results On seasonal and non-seasonal scales, satellite altimetry measurements are well explained by the summation of time-variable gravity and Argo floats, demonstrating the closure of coastal sea level change.Satellite altimetry suggests a rate of 3.32±0.45 mm/a for coastal sea level rise, but the summation of time-variable gravity and Argo floats yields a rate of 2.25±0.51 mm/a.
Conclusions The rate discrepancy is about 1 mm/a in coastal sea level budget, which suggestes that closing the sea level budget for coastal zone is challenged by uncertainties. The in situ measurements are sparse for Argo over coastal zone, which may underestimate the steric trend. Furthermore, leakage correction and vertical land motion may also cause uncertainties.
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