Analysis of Temporal Variations in Significant Wave Height in the Circum-Bohai Sea Based on Multi-Satellite Merged Data

Wave height is a critical parameter for marine hazard warning systems and the structural safety of offshore engineering. The Bohai Sea and its surrounding region is an important economic hub in northern China and serves as the maritime route for the coastal provinces of North, Northwest, and Northeast China. Therefore, the sea state in the Circum-Bohai Sea has a significant impact on the Bohai economic circle. This study analyzes and summarizes the medium-term variation trends of waves in the Circum-Bohai Sea based on multi-source satellite data (AVISO/Copernicus dataset) from 2009 to 2025. The results indicate that the Significant wave height (SWH) in the Circum-Bohai Sea is mainly dominated by wind waves, exhibiting significant seasonal variation characteristics. The significant wave height in winter exhibited a consecutive decline from 2014 to 2018, with a reduction of approximately 14%. Spectral analysis reveals the existence of one-year, half-year, and two-year cyclical variation signals in the SWH of the Circum-Bohai Sea. This study provides a scientific foundation for marine hazard early warning systems, offshore engineering safety assessments, and climate change adaptation strategies in the Bohai Economic Rim.