Spectral properties of Surface Water and Ocean Topography (SWOT) satellite altimetry data offshore eastern Mindanao

Abstract

The Philippine archipelago is characterized by complex tectonic structures and steep bathymetric gradients that require high-fidelity marine gravity data for accurate geophysical modeling. While the new Surface Water and Ocean Topography (SWOT) mission's Ka-band Radar Interferometer (KaRIn) promises unprecedented 2D sea surface observations, its specific quality and effective resolution in a geographically diverse region such as the Philippines is yet to be quantified. This study evaluates the quality of SWOT data around the Philippines by performing 1D spectral analysis on a pair of 39-cycle stacks of sea surface slope (SSS) data from offshore eastern Mindanao. By calculating the power spectral density (PSD) and spectral coherence between the pair of stacks, we identified the noise and resolution limit of the SWOT-derived data. Our results indicate that SWOT demonstrates a noise dominant threshold of 12.5 km and an effective resolution limit of 14.5 km in the study region offshore eastern Mindanao. Our assessment establishes a new baseline for the application of interferometric altimetry in Philippine marine geophysics and tectonic studies.