Potential of time-series InSAR analysis for measuring localized ground motion at Tide gauges for improved sea level change observations

Relative sea level changes that recorded by tide gauges installed around the world, are used to reconstruct the global and regional sea level changes. As these tide gauges are installed at the coastal lines are vulnerable for various natural and man-made coastal processes. Vertical ground motion is one such coastal processes that affects the relative sea level change observations. Recent studies include GNSS techniques and space-borne Interferometric (InSAR) techniques are used to estimate the vertical ground motion along the vulnerable coastlines.

In this study, we investigates the vertical land motion at selected tide gauges and its vicinity located in South Korea using time-series InSAR technique. For more than Half-a-century, about 21 tide gauges have been continuously recording the relative sea level changes (according to PSMSL database). South Korea is a peninsular country located in the Eastern Asia have surrounded by East Sea, yellow sea and East china sea. Among these tide gauges, the spatial difference in relative sea level changes were observed. In addition, tide gauge stations such as Jeju, Pohang have shown significant sea level rise in the recent years than global sea level rise. Persistent Scatterers Interferometric SAR (PS-InSAR) is a well-known remote sensing technique that widely used to measure the ground displacement in the line of sight direction. In our analysis, we use C-band Sentinel-1 SAR data from acquired during 2014 - 2019 to estimate the time-series ground motion at the vicinity of vulnerable tide gauge locations. Comparison is made with the available co-located GNSS observations and InSAR ground motions.