Study on Ground-based Radar Observations for Sea Level Change Detection

Abstract

Monitoring sea-level variations in tidal flats is essential for managing coastal flooding, environments, and aquaculture facilities. However, South Korea’s large tidal range limits spaceborne remote sensing observations, necessitating continuous datasets with high spatiotemporal resolution. In this study, time-series radar observations were acquired at 2-min intervals for approximately 7 hours over the Jeungdo tidal flat (Sinan County, Jeollanam-do, South Korea) using a Ku-band ground-based microwave radar system, the Gamma Portable Radar Interferometer-II (GPRI-II). This study aimed to establish a high-temporal-resolution ground-based radar observations and characterize changes in backscatter intensity, interferometric coherence, and interferometric phase of coastal aquaculture structures in relation to rising tidal levels. These observables were compared with in situ tidal-level measurements from the Hyanghwado tide gauge station, located approximately 29 km from the study area, with the tidal timing difference between the two locations considered. The results showed that backscatter intensity and interferometric coherence generally decreased as the tidal level rose, while the standard deviation of the interferometric phase increased. The intensity images clearly captured the spatial expansion of the seawater surface and the progressive inundation of aquaculture structures. Furthermore, coherence and interferometric phase measurements continuously reflected changes in scattering behaviors driven by sea-level variations. This study demonstrates how ground-based radar can produce high-temporal-resolution coastal datasets, characterize spatiotemporal signal variations, and highlight its potential for monitoring coastal water-level changes.