Resolution of SWOT Altimetry: Improvements Along Continental Margins

Abstract

The along-track sea surface slopes (SSS) computed from the Surface Water and Ocean Topography (SWOT) measurements are extremely important in the retrieval of high-resolution global marine gravity anomalies. We estimate the spatial resolution of SWOT measurements and assess the inherent improvements offered by wide-swath altimetry over 12 sites representing the continental margins of the Pacific, the Atlantic and the Indian Oceans. We perform power and cross-spectral analysis on pair of along-track SSS profiles to determine the noise limit and resolution. Individual SWOT cycles can deliver SSS with a spatial resolution of ∼10–20 km along the continental margins. We further average 54 cycles of along-track SSS data at each site into pairs of SWOT stacks. Stacking reduces the ocean dynamics by an order of magnitude, even in the areas dominated by strong oceanographic variability and improves the resolution to ∼5–10 km. The spatial resolution determined from SWOT stacks offers a two-fold improvement compared to the short-wavelength resolution estimated from nadir altimetry along the continental margins. The study suggests that SWOT measurements would substantially improve the resolution of altimeter-derived marine gravity over global continental margins.