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MARI/CCPO Seminar Series
Analyzing Past and Present Sea Level Around the Korean Peninsula
Se-Hyeon Cheon, Seoul National University
Accurate comparisons between past and present climate variations require long and consistent data records. Two primary sources of sea level measurements over the past century are: 1) tide gauges with long records but poor spatial coverage, and 2) satellite altimetry with near-global spatial coverage but short (~20 years) length. Sea level reconstructions are formed by using the spatial patterns from the satellite altimetry and fitting to the long tide gauge records. The result is a dataset with the record length of the tide gauges and the spatial coverage of the satellite altimetry. Using these methods, Hamlington et al. (2012) extended the sea level record back to 1900. On global scales, the reconstruction of Hamlington et al. (2012) shows significant improvement in terms of the ability to accurately represent regional sea level variability when compared to other reconstructions. On regional and local scales, however, questions remain regarding the information such reconstructions can provide.
In Korea, natural disaster rates around coastal zones are increasing, which have been attributed to chance events or climate change. By examining sea level in the region, we can begin to address the causes of the increasing rate, while simultaneously evaluating ways to improve reconstructions on regional scales. In this study we reconstruct the sea level around the Korean Peninsula from 1900 to 2013 using observational data and the CSEOF (cyclostationary empirical orthogonal function) bivariate reconstruction method. CSEOFs derived from satellite altimetry are first fit to historical sea level measurements from tide gauges in the region. Then, to improve the reconstruction performance, we incorporate sea surface temperature measurements using the technique of Hamlington et al. (2012). The results are compared to the satellite altimetry, tide gauge data and global reconstructions. The potential applications of this work are outlined and discussed in terms of how we can gain an improved understanding of future sea level around the Korean Peninsula.