CoAuthors

Ananda Pascual (IMEDEA (CSIC-UIB), Balearic Islands, Spain); Marie Isabelle Pujol (CLS, Toulouse, France); Guillaume Taburet (CLS, Toulouse, France); Marta Marcos (IMEDEA (CSIC-UIB), Balearic Islands; UIB, Balearic Islands, Spain); Yannice Faugère (CLS, Toulouse, France)

In this work we assess the quality of 1Hz Sentinel-3A Level-3 along-track DUACS dataset in the coastal area of the European Seas over a period of two and half years from May 2016 to September 2018 through a comparison with in-situ tide gauge measurements. The comparison is also conducted by using altimetry data from Jason-3 for inter-comparison purposes. To do that, we compare the equivalent SLAs derived from 6-hour sampled tide gauges over the same period in the whole domain and the following sub-regions: Mediterranean and Baltic Seas; and the IBI and NWS regions. Tide gauge records disseminated on CMEMS were used.

We found that Sentinel-3A improved the root mean square errors by 13% with respect to Jason-3 mission. In addition, the variance of the differences between the two datasets was reduced by 25% and the mean of the distance between tide gauge sites and the most correlated altimetry track points was reduced by 9%. To explain the improved capture of Sea Level Anomaly by Sentinel-3A in the coastal band, the impact of the measurement noise on the synthetic aperture radar altimeter, the distance to coast, and the Long Wave Error correction applied on altimetry data were checked. Results confirmed that synthetic aperture radar altimeter instrument on board the Sentinel-3A mission better solves the signal in the coastal band. Moreover, the Long Wave Error processing contributes to reduce errors in altimetry enhancing the consistency between altimeter and in-situ datasets.