The issue of estimating a global mean dynamic topography (MDT) is to reference the altimetric Sea Level Anomalies (SLA), computed relative to a 7 year (1993-1999) mean profile, in order to obtain absolute measurements of the ocean dynamic topography. Required MDT has to be consistent with altimetric physical content and shall therefore correspond to: The mean over 1993-1999 of the geostrophic, barotropic and baroclinic oceanic circulation. This work combines several steps [1], [3]:

1. We first use the so-called the direct method to estimate at large scale  a MDT using the CLS01 MSS and the EIGEN-2 CHAMP geoid. The direct method MDT is then merged with the Levitus climatology MDT to provide our first guess.

2. Then we use the synthetic method to improve the mean circulation of this first guess, using hydrographic and Lagrangian data together with altimetric Sea Level Anomalies over the 1993-1999 period. The global MDT has then been compared to others surfaces.

3. Finally, we used independant drifter data to compare the CMDT RIO-03 with OCCAM, Levitus, and Le Grand derived MDT.

• To access to the Combined Mean Dynamic Topography RIO-03 (FTP access), please contact Fabrice Hernandez.

• the corresponding errors:

• the corresponding mean geostrophic velocities (not computed in the equatorial band):