Between 1993 and 1998, the global mean sea level (MSL) has been known to be affected by an instrumental drift in the TOPEX-A measurements which has been quantified by several studies (Watson et al., 2015, Dieng et al. 2017; Beckley et al., 2017).
The altimeter sea level community agrees that it is necessary to correct the TOPEX-A record for the instrumental drift to improve the accuracy and the uncertainty of the total sea level record. However, there is not yet consensus on the best approach to estimate the drift correction on global and regional scales. The recommendation of the Ocean Surface Topography Science Team (OSTST) is to wait for the future release of a reprocessed TOPEX dataset.
Therefore, the DUACS altimeter mean sea level products are not corrected for the TOPEX-A drift but the users can apply their own correction.