Spatiotemporal sea level change around Japan Sea from satellite altimetry and in situ observation with EOF analysis from 1993 to 2020

We investigate the spatiotemporal characteristics of sea level change (SLC) in Japan's territories by analyzing tide gauge (TG) records and satellite altimetry (SA) data from 1993 to 2020. The analysis reveals that the relative sea level change (RSLC) rate in Japan is 2.20 ± 0.62 mm/a, while satellite altimetry (SA) data calculate an absolute sea level change rate (ASLC) of 3.13 ± 1.66 mm/a. Additionally, some TG stations show significant sea level subsidence rates, primarily attributed to vertical land movement (VLM), particularly the land uplift effect in localized regions, leading to negative RSLC. After correcting for VLM, the recalculated SLC rate is 3.77 ± 1.26 mm/a, which is consistent with the value of 3.4 mm/a reported by the Japan Meteorological Agency. Through Empirical Orthogonal Function (EOF) analysis, the primary spatial patterns of change in both SA and TG data exhibit a high degree of consistency, with the first mode contributing 80.24 % and 82.95 % of the variance, respectively. The first mode of EOF for the coastal sea level represents a simultaneous (SLC) along the whole Japanese coast and the second mode is closely related to the Kuroshio Large Meander (LM), Further, extract the dominant components of sea level variation, and denoising was performed on the TG data. Compared to the Raw data, the denoised data showed a root mean square (RMS) error reduction of 6.98 mm on average, with uncertainty decreasing by 0.25 mm/a. These results provide important insights for more accurate SLC trend estimation.