The Extraction of Ocean Tidal Loading from ASAR Differential Interferograms

Area of Science:

• Geodesy
• Remote Sensing
• Earth Sciences

Background:

• Ocean tidal loading (OTL) induces significant non-tectonic crustal deformation in coastal regions, reaching centimeter scales.
• Global Positioning System (GPS) can estimate temporal OTL displacements, but spatial variations require further investigation.

Purpose of the Study:

• To develop and validate a multi-scale decomposition method for deriving ocean tidal loading displacements from D-InSAR measurements.
• To analyze the spatial characteristics of OTL displacements and compare them with GPS and tide models.

Main Methods:

• Proposed a multi-scale decomposition method based on signal spatial characteristics to extract OTL displacements from D-InSAR data.
• Utilized long-term Advanced Synthetic Aperture Radar (ASAR) data and GPS reference site data from the Los Angeles Basin.
• Compared derived OTL displacements with the FES2014b tide model.

Main Results:

• The spatial function of OTL displacements in ASAR images was represented as a higher-order polynomial.
• Spatial trends of OTL displacements derived from InSAR and GPS were consistent with the FES2014b tide model.
• Root-mean-square errors between InSAR/GPS-derived and FES2014b OTL displacements were less than 0.8 mm.

Conclusions:

• InSAR data, processed with the proposed method, accurately reflects the spatial characteristics of OTL effects.
• This approach enhances the spatial resolution and accuracy of OTL displacement estimations in coastal areas.
• The findings contribute to a better understanding of non-tectonic crustal deformation phenomena.