Detection capabilities of a multi-satellite wide-swath altimetry conceptual mission

The soon-to-be available swath altimetry observations from the SWOT mission are expected to drastically improve our capacity to observe fine-scale ocean processes (wavelengths shorter than 100 km). With its increased observing capacity and lower signal-to-noise (SNR) ratio in comparison to conventional nadir altimetry, this new technology is expected to deliver unprecedented high-resolution two-dimensional observations of the ocean surface circulation and surface water bodies. Benefiting from the technological maturity acquired during the preparation for SWOT, a new constellation concept composed of swath altimeters has been proposed to carry on the European operational observing system towards the end of the decade. In the present work, we focus on evaluating the ocean observing capabilities of a novel swath altimeter concept (WiSA – Wide Swath Altimeter). Using the observed surface wave field (SWH – Significant Wave Height) and the instrumental characteristics, we compute global estimates of the SNR. We observe an average global observability around 40 km wavelength over 50% of the global ocean, and 47 km on average over 80% of the globe. Little or no seasonality is observed in the SNR, related to the seasonal compensation of the two competing factors that contribute to the observability, namely the instrumental noise levels and the observed spectral slopes. The performance of recently developed data-driven filtering techniques is also evaluated, considerably increasing the purely instrumental observing capabilities. The results are also discussed from an operational perspective, considering the contribution of a constellation of swath altimeters over a mono-satellite mission.