Ssalto/Duacs monthly and DAILY mean sea level anomalyBy: Stefan Kern
Up-to-Date data set replaced by (shorter) reference data set
We carried out an investigation of monthly mean sea level anomaly (MSLA) using "Up-to-Date" (UPD) and "Reference" (REF) data provided by Ssalto/Duacs. UPD MSLA gives a longer data set (until Nov. 2011) and is said to be more accurate than the REF MSLA (until March 2010) because up to four altimeters instead of two are used; REF MSLA is said to be more homogeneous in time. We compared REF and UPD MSLA averaged over 3 ° x 3° grid boxes in five different regions world-wide with different typical seasonal cycles of the MSLA. The mean MSLA and the standard deviation of the MSLA within these boxes differs between REF and UPD MSLA by up to 5 cm starting in 1999/2000 while these agree with each other within 1 cm before. This inconsistency over time motivated us to change the currently offered MSLA data set from the longer UPD to the shorter REF. This data set is now available via http://icdc.zmaw.de/ssh_aviso.
In addition, we are pleased to inform you that we now offer the daily MSLA as well as anomalies of the surface current vector which are accessible under the same link.