Absolute Sea Level Changes Along the Coast of China From Tide Gauges, GNSS, and Satellite Altimetry

This study quantifies the absolute sea level (ASL) change along the coast of China from 1993 to 2019 using tide gauge (TG) and Global Navigation Satellite System (GNSS) data. The sea level change at 12 collocated TG and GNSS stations along the Chinese coast are first analyzed by TG + GNSS data. Then the ASL rise and its spatial variation along the coast of China and that in surrounding oceans are studied using TG + GNSS data and satellite altimetry products. The results show that the relative sea level rise along the Chinese coast varied from 2.61 +/- 0.76 to 5.56 +/- 0.70 mm/yr, while the effect of vertical land motion (VLM) ranged from -1.46 +/- 0.30 to 1.07 +/- 0.38 mm/yr. After correcting the effect of the VLM, the ASL rise ranged from 2.51 +/- 0.86 to 5.03 +/- 0.60 mm/yr, with a mean rate of 3.94 +/- 0.88 mm/yr, which was 0.7 mm/yr higher than the global average. It is found that ASL rise rate is significantly higher in Chinese seas and neighboring oceans, with a meridional distribution in the East China Sea and a zonal distribution in the South China Sea. This may be related to factors such as sea surface temperature rise, atmospheric pressure decrease, freshwater runoff, zonal wind stress anomaly, and alongshore currents in the area.