Enhanced resolution capability of SWOT sea surface height measurements and its application in monitoring ocean dynamics variability

Abstract. The wavenumber spectrum of sea surface height along ground profiles is commonly determined to quantify the magnitude of detectable ocean dynamic features by altimetry missions. In this paper, wavenumber spectral were calculated and compared for HY2B, Saral/AltiKa, Sentinel-3A, and SWOT. The wavenumber power spectral density(PSD) of sea surface height (SSH) was averaged using weighted methods across multiple along tracks within defined boxes. The deduced resolution capabilities were also compared and analyzed, evaluated using the relevant definition of one-dimensional mesoscale resolution capability. We verified that the latest wide-swath SWOT mission offers significantly improved measurements. For example, in the vicinity of Kuroshio, the one-dimensional mesoscale resolution of SWOT is about 25 kilometers, twice the resolution capability of conventional satellites. In addition, the quality of measurements declined obviously over regions where the eddy kinetic energy gets larger. Finally, a global analysis of ocean dynamics variability scales was conducted based on two cycles of SWOT data using reciprocal power spectral analysis. The results showed significant geographic and temporal variations in the ocean dynamics variability scales, which are mainly relative to sea state variability. The regions with large scales of ocean dynamics variability are concentrated in oceans with strong currents and unstable sea states, such as the Kuroshio Current, the Gulf Stream, and the Antarctic Circumpolar Current. In addition, the scale of ocean dynamics variability is not necessarily large where eddy kinetic energy is large, such as the equator and the northwest Indian Ocean current area. Ocean dynamics variability also varies across seasons.