Regional projection of sea level rise: the Seto inland sea case in Japan

Abstract

The future sea level rise (SLR) in the year of 2050 and 2100 are estimated by using ensemble empirical mode decomposition (EEMD) with long-term sea level records in and around the Seto Inland Sea, Japan. Ensemble empirical mode decomposition, an adaptive data analysis method, can separate the sea level records into intrinsic mode functions (IMFs) from high to low frequency and the residue. The residue is considered as the non-linear trend from the sea level records. The SLR trend at Tokuyama in the Seto Inland Sea obtained from EEMD is 3.58 mm/yr over 1993-2010, which is slightly larger than the recent altimetry-based global rate of 3.3 ± 0.4 mm/yr over 1993-2007. Then, the non-linear trend is utilized to project the regional SLR in the Seto Inland Sea. The resulting SLR in 2050 and 2100 estimated are 0.18 m and 0.49 m at Tokuyama, respectively. The SLR is not only due to mass and volume changes of sea water, but also due to other factors such as local subsidence, river discharge and sediments, and vegetation effect. The non-linear trend of SLR, which is the residue from EEMD, can be regarded as a final consequential sea level after considering those factors and their nonlinearity. The EEMD method can be useful tool not only for the SLR projection under climate change, but also for observed data analysis in coastal engineering and hydrology.