The Extraction of Ocean Tidal Loading from ASAR Differential Interferograms

Abstract

The spatiotemporal crustal non-tectonic deformation caused by ocean tidal loading (OTL) can reach the centimeters scale in coastal land areas. The temporal variation of the site OTL displacements can be estimated by the global positioning system (GPS) technique, but its spatial variation needs to be further determined. In this paper, in order to analyze the spatial characteristics of the OTL displacements, we propose a multi-scale decomposition method based on signal spatial characteristics to derive the OTL displacements from differential interferometric synthetic aperture radar (D-InSAR) measurements. The method was tested using long-term advanced synthetic aperture radar (ASAR) data and GPS reference site data from the Los Angeles Basin in the United States, and we compared the results with the FES2014b tide model. The experimental results showed that the spatial function of the OTL displacements in an ASAR image can be represented as a higher-order polynomial function, and the spatial trends of the OTL displacements determined by the InSAR and the GPS techniques are basically consistent with the FES2014b tide model. The root-mean-square errors of the differences between the spatial OTL displacements of these two methods and the FES2014b tide model are less than 0.8 mm. The results indicate that the OTL displacement extracted from InSAR data can accurately reflect the spatial characteristics of the OTL effect, which will help to improve the spatial resolution and accuracy of the OTL displacement in coastal areas.

Ocean Wave Energy Harvesting via Scotch Yoke-based Rotational Generation

“…Yoke-based Rotational Generation ocean are thermal (temperature difference) [20], [21], ocean current [22], tidal [23], and wave energy [24], [25], [26], [27].…”

Spatiotemporal Ocean Tidal Loading in InSAR Measurements Determined by Kinematic PPP Solutions of a Regional GPS Network

“…The kernel function of the LSSVM method is based on the spatial characteristics of the tidal constituents. The spatial trend of the OTL displacements from coast to inland are close to the bivariate polynomial [6]. In this paper, we further consider the selection of the kernel function based on the spatial variation of the phasors of the tide model and the PPP tidal estimates.…”

“…HE Interferometric synthetic aperture radar (InSAR) is a powerful tool for mapping the Earth's ground displacements, and the Sentinel-1 measurements in coastal areas usually contain tectonic deformation, atmospheric delay, the ocean tidal loading (OTL) effect, solid Earth tidal (SET) effect, orbital error, residual topographic phase error, and decorrelation noise [1][2][3]. The OTL effect is the response of the solid Earth to ocean mass redistribution due to the gravitational force changes, its gradient nonlinearly decreases from cm/100km scale in the coastal area to mm/100km scale in the area 200 km away from the coast [4][5][6]. For the other spatial large-scale signals, the spatial wavelength of the SET effect is more than one order larger than the OTL effect, and its spatial variation in the range of the Sentinel-1 SLC image tends to be a lower-order curve [7]; The atmospheric delay maps provided by the Generic Atmospheric Correction Online Service for InSAR (GACOS) and precise orbital files are commonly used to reduce atmospheric delay and the orbital error [8,9].…”