Abstract
It is vital to improve estimations of long-term trends in global and regional sea level rise to help mitigate and adapt to climate change. Satellite altimetry data have been widely used for this purpose; however, data collected in regions with strong tidalmotions often suffer from significant aliasing effects unless they are sufficiently corrected using accurate ocean tide models.Long-term trends estimated from altimetry data are often also considerably affected by regional circulation changes, and by artificial effects arising from inconsistencies between different satellite missions. Here, we focused on two regions with high (>5 mm⋅yr–1) rates of long-term linear trend in sea level rise (LTSLR) around the Korean Peninsula (KP). We addressed the impacts of tidal correction and mission inconsistency in satellite altimetry data, and discussed the potential impacts of circulation changes on LTSLR. Because the LTSLR estimation is affected by the aliasing effects of altimetry data when the tidal motions are not corrected sufficiently, yet the correction depends on the performance of ocean tide models, we employed eight ocean tide models to correct altimetry data for comparison and validated the results against observations from 13 tide gauge (TG) stations around the KP. We also estimated LTSLR from 1993 to 2019 using annual mean sea level anomalies (SLAs) from two satellite (two-sat) and all 21 satellite (all-sat) missions, with corrections for ocean tides. The TPXO9 model showed the most reasonable spatial LTSLR rate pattern (∼3 mm⋅yr–1), with the smallest difference from TG observations. It performed best near the west coast where the tidal range was the largest and when using two-sat data, because of inconsistencies in all-sat altimetry data. In contrast, off the east coast, where the impact of tidal correction is negligible, the high (∼7 mm⋅yr–1) LTSLR rates were robust regardless of ocean tide models and altimetry missions, potentially driven by long-term changes in regional circulation. Our results highlight the importance of tidal correction and mission inconsistency for improving LTSLR estimations around the KP. They also have significant implications for determining regional sea level rise under changing circulation patterns, within and beyond the region.
Highlights
Global mean sea level rise is currently accelerating (IPCC, 2019); the ability to accurately evaluate long-term trends in regional sea level rise, which often deviate from the global trend, is becoming increasingly important (Cazenave and Llovel, 2010; Nicholls and Cazenave, 2010; Church and White, 2011; Stammer et al, 2013)
It is noteworthy that the Finite Element Solution 2014 (FES2014) model, which is used in the operational production of Copernicus Marine Environment Monitoring Service (CMEMS) L3 sea level anomalies (SLAs), was outperformed by the TPXO9, where the latter yielded overall minimum RMS difference as the ocean tides in the region are best simulated by the TPXO9 model (Figure 4)
This study revealed that corrections for ocean tides and mission inconsistencies in satellite altimetry data can both significantly impact the estimation of linear trend in sea level rise (LTSLR) in regions with strong tidal motions near the west coast of the Korean Peninsula (KP)
Summary
Global mean sea level rise is currently accelerating (IPCC, 2019); the ability to accurately evaluate long-term trends in regional sea level rise, which often deviate from the global trend, is becoming increasingly important (Cazenave and Llovel, 2010; Nicholls and Cazenave, 2010; Church and White, 2011; Stammer et al, 2013). In addition to long-term sea level rise, the sea level around the KP significantly changes at interannual and decadal timescales in relation to large-scale patterns of climatic variability, such as the Pacific Decadal Oscillation (Cheng et al, 2015; Kim et al, 2018) and Arctic Oscillation, via changes in sea surface temperature and air-sea heat exchange (Park et al, 2015) These changes are driven by regional circulation and the upper ocean heat content (Choi et al, 2004, 2009; Kang et al, 2005; Yoon et al, 2016; Pak et al, 2019). Despite these previous studies on the processes underlying interannual and decadal variations in sea level around the KP, the physical drivers and data issues influencing the high LTSLR rates near the west coast and off the east coast remain poorly understood
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