Mass-Induced Seasonal Sea Level Variability from Geodetic Observations: A Case Study Along the Eastern Coast of China

Summary Seasonal mass changes along shorelines have been largely overlooked due to the coarse spatial resolution of the Gravity Recovery and Climate Experiment (GRACE) measurements. Here, we examine the monthly mean ocean mass along the east coast of China using GRACE data and identify a pronounced seasonal cycle and its southward propagation, with peak-to-peak amplitudes of ~150 mm, reaching the minimum in April and maximum in October, opposite in phase to seasonal mass changes over adjacent land. Independent estimates from satellite altimetry sea level anomalies corrected for thermosteric effects and GNSS displacements confirm the GRACE results, all revealing significant seasonal ocean mass changes in this region. Furthermore, wind-stress forced model simulations effectively replicates both the phase and magnitude of the observed variations, demonstrating that wind stress is the primary driver of the seasonal ocean mass changes and southward propagating transports.