remote sensing Technical Note Annual Sea Level Amplitude Analysis over the North Pacific Ocean Coast by Ensemble Empirical Mode Decomposition Method Wen-Hau Lan 1 , Chung-Yen Kuo 2 , Li-Ching Lin 3 and Huan-Chin Kao 2,* 1 Department of Communications, Navigation and Control Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan;
[email protected] 2 Department of Geomatics, National Cheng Kung University, Tainan 70101, Taiwan;
[email protected] 3 Department of System Engineering and Naval Architecture, National Taiwan Ocean University, Keelung 20224, Taiwan;
[email protected] * Correspondence:
[email protected]; Tel.: +886-06-275-7575 (ext. 63833-818) Abstract: Understanding spatial and temporal changes of seasonal sea level cycles is important because of direct influence on coastal systems. The annual sea level cycle is substantially larger than semi-annual cycle in most parts of the ocean. Ensemble empirical mode decomposition (EEMD) method has been widely used to study tidal component, long-term sea level rise, and decadal sea level variation. In this work, EEMD is used to analyze the observed monthly sea level anomalies and detect annual cycle characteristics. Considering that the variations of the annual sea level variation in the Northeast Pacific Ocean are poorly studied, the trend and characteristics of annual sea level amplitudes and related mechanisms in the North Pacific Ocean are investigated using long-term tide gauge records covering 1950–2016. The average annual amplitude of coastal sea level exhibits interannual-to-decadal variability within the range of 14–220 mm. The largest value of ~174 mm is observed in the west coast of South China Sea.