Sea level patterns around Korea and Japan

Abstract

The relative sea levels are the sum of one sea and one land component. Similar to the sea component, which is characterized by an accelerating pattern because of the thermostatic effect, the land component is characterized by an accelerating pattern because of growing subsidence. This work discusses the relative sea level patterns of Korea and Japan since the end of the 1800s. Korea has no long-term trend tide gauge of sufficient quality and length to evaluate a reliable velocity and acceleration of the sea level. On the contrary, in Japan, there are many long-term trend tide gauges recording the sea levels since 1894. The tide gauges of Hosojima, Wajima, Tonoura, and Oshoro, not suffering from subsidence or isostasy, show multi-decadal fluctuations of periodicity quasi-20 and quasi-60 years, but not rising, nor accelerating, relative sea levels. From the similarity of the patterns in the relative sea levels measured by tide gauges in Korea and the west coast of Japan since the 1960s and the similar pattern for the absolute sea levels from satellite altimetry since 1993, very likely Korea has growing relative sea levels since the 1960s only because of subsidence and short term time window.