[A-CG37] Satellite Earth Environment Observation

[ACG37-P16] Long-term sea level trends around Taiwan revealed by satellite altimetry and nearshore tidal gauge data

*Yen-Chen Huang¹, Ming-Huei Chang^1,2, Yu-Hsin Cheng³ (1.Institute of Oceanography, National Taiwan University, 2.Ocean Center, National Taiwan University, 3.Department of Marine Environmental Information, National Taiwan Ocean University)

Keywords:Global warming, Sea Level Rise, Satellite remote sensing, Taiwan coast, North Pacific

The global mean sea level has risen 220 mm since 1880 as a result of the combination of meltwater from glaciers and ice sheets and the thermal expansion of seawater as it warms. It suggests a rising rate of ~1.7 mm/yr, which has been known to accelerate significantly in recent years. Since it affects marine ecology and intensifies disastrous weather events, it is critical to quantify the rising trend of sea level, which could vary significantly in the world ocean. In this study, we analyze the tidal level data around Taiwan provided by the Central Weather Bureau of Taiwan (CWB) and the global ocean gridded Level-4 Sea Surface Heights (SSH) satellite observation data provided by Copernicus Marine Environment Monitoring Service (CMEMS) to understand the long-term trend of sea level around Taiwan. The results of CWB data analysis show that the average sea level rise rates in the recent 10 years and 20 years are 7.74 mm/yr and 5.18 mm/yr, respectively. By contrast, in the analysis of satellite data around Taiwan (116°E to 130°E, 18°N to 30°N), the average sea level rise rate in recent 10 years is 6.93 mm/yr, while the average rate of sea level rise in recent 20 years is 2.73 mm/yr. The 10-yr rate is close to that from the CWB data, but the 20-yr rate is only 53% of that from the CWB data. By using the satellite data, the average sea level rise trend around Taiwan from 2001 to 2020 is slightly lower than the average of the North Pacific region (3.19 mm/yr) and the global mean value (3.73 mm/yr), and the average sea level rise from 2011 to 2020 is higher than the average of the North Pacific region (5.34 mm/yr) and the global mean value (4.44 mm/yr).