CoAuthors

Ngan Tran (CLS, France); Thibault Pirotte (CLS, France); Mohamed Mrad (CLS , France); Hélène Etienne (CLS, France); Thomas Moreau (CLS, France); François Boy (CNES, France); Claire Maraldi (CNES, France); Craig Donlon (ESA, Holland)

The S6-MF mission continues to serve the innovative record of the Delay/Doppler altimeter technique started with the Cryosat-2 mission and continued with S3-A/B. This technique has opened a new era for altimetry thanks to its significant advantages over conventional altimetry in terms of improved measurement errors and finer spatial along-track resolution, which logically raises the question of the observability of the small oceanic structures. However, to extract relevant information on these small scales, we need to better understand how ocean phenomena such as waves, wave motion, roughness, currents, etc., impact this signal and the associated geophysical estimates.
Various researchers have been interested in understanding the sensitivity of delay/Doppler measurements to surface characteristics: waves and swell and their direction with respect to the satellite direction, orbital speeds, etc... More recently, sensitivity to wind direction has been observed in Sentinel-3 and Sentinel-6 data.
The aim of this study is to further evaluate the impact of ocean wave dynamics on the estimates of significant wave height and sea surface height from Sentinel-6MF delay/Doppler measurements. In addition to vertical velocities, we analyzed the impact of wind speed and direction, the impact of Stokes drifts and finally the impact of total surface currents. For this, we used a year of real Sentinel-6MF data and information on waves and currents from the ERA5 and MERCATOR models. A theoretical analysis was also carried out to explain the observed behaviors.
The results of these analyzes will be reported in this presentation.