Abstract's details

New CNES-CLS18 Mean Dynamic Topography of the global ocean from altimetry, gravity and in-situ data

Sandrine Mulet (CLS, France)


Marie-Hélène Rio (ESA, Italy); Hélène Etienne (CLS, France); Nicolas Picot (CNES, France); Gérald Dibarboure (CNES, France)

Event: 2019 Ocean Surface Topography Science Team Meeting

Session: The Geoid, Mean Sea Surfaces and Mean Dynamic Topography

Presentation type: Type Oral

Contribution: PDF file


The Mean Dynamic Topography (MDT) is a key reference surface for altimetry. It is needed for the calculation of the ocean absolute dynamic topography, and under the geostrophic approximation, the estimation of surface currents. Those are required for a wide range of applications as the management of fishery resources, the monitoring of potential pollution, maritime security… Also, the MDT is the missing component for the optimal assimilation of altimeter data into operational ocean system as those run under the Copernicus Marine Environment Monitoring Services (CMEMS).

CNES-CLS Mean Dynamic Topography solutions are calculated by merging information from altimeter data, GRACE and GOCE gravity data and oceanographic in-situ measurements from drifting buoy velocities and hydrological profiles. The objective of this communication is to present the newly updated CNES-CLS18 MDT. The main novelties compared to the previous CNES-CLS13 solution is the use of updated input datasets: the GOCO05S geoid model (instead of DIR4) and the CNES-CLS15 Mean Sea Surface are used together with drifting buoy velocities (SVP-type and Argo floats) and hydrological profiles (CORA database) available from 1993 to 2016 (instead of 1993-2012). The new solution also benefits from improved data processing (in particular, a new Ekman model is used to extract the geostrophic component from the buoy velocities) and methodology.

An evaluation of this new solution compared to the previous version and to other existing MDT is done through comparison to independent in-situ data. Further validation by “super-users” have also been performed. Compared to the CNES-CLS13 solution, the new CNES-CLS18 MDT shows improved performance everywhere and more significantly in coastal areas and in strong western boundary currents.

Oral presentation show times:

Room Start Date End Date
The Monroe Hub Thu, Oct 24 2019,09:30 Thu, Oct 24 2019,09:45
Sandrine Mulet