The French SSALTO/DUACS multimission altimeter processing system combines data from all altimetric satellites to produce a near-global product of absolute and relative sea surface height. SSALTO stands for Segment Sol multi-missions dALTimetrie, d’orbitographie et de localisation precise; DUACS stands for Data Unification and Altimeter Combination System, or Developing Use of Altimetry for Climate Studies. The data set provides a near-global data set of geostrophic currents (idea for this post is courtesy Lei Wang).
SSALTO/DUACS processes data from all altimeter missions, including the Chinese HY-2A, Saral/AltiKa, Cryosat-2, OSTM/Jason-2, Jason-1, Topex/Poseidon, Envisat, GFO, ERS- 1&2 and even Geosat. From each satellite, SSALTO/DUACS uses the Interim Geophysical Data Record (IGDR), where these are 1-second averages available within 3 days of data collection, from all altimeters. For greater accuracy, the reader should use the GDR, which is a validated record available with a 6-week time lag. Examination of the image shows that the combined product provides data north into Arctic and south to the Antarctic coast. The website for the system and directions on obtaining data are at http://www.aviso.altimetry.fr/en/data/product-information/information-about-mono-and-multi-mission-processing/ssaltoduacs-multimission-altimeter-products.html; the handbook for the data set is at http://www.aviso.oceanobs.com/fileadmin/documents/data/tools/hdbk_duacs.pdf