DUACS DT2021 reprocessed altimetry improves sea level retrieval in the coastal band of the European Seas

Abstract. More than 29 years of altimeter data have been recently reprocessed by the multi satellite Data Unification and Altimeter Combination System (DUACS) and made available under the name of DT2021 processing through the Copernicus Marine Service (CMEMS) and the Copernicus Climate Change (C3S) Service. New standards have been applied and various geophysical correction parameters were updated compared to the previous release in order to improve the product quality.

This paper describes the assessment of this new release through the comparison of both all satellites and two satellites products with external in situ tide gauge measurements in the coastal areas of the European Seas. The aim is to quantify the improvements on the previous DT2018 processing version on the retrieval of sea level in the coastal zone.

The results confirmed that the new DT2021 processing version better solves the signal in the coastal band. Moreover, the all satellites dataset provided more accurate sea level measurements when comparing with tide gauges respect to the climatic two satellites dataset due to the better performance of the former for the assessment of higher than climatic frequency signals. On the opposite, we found the two satellite dataset the most suitable product for the assessment of long term sea level time series in the coastal zone due to its larger stability to the detriment of the all satellites dataset.