On the resolution of ocean altimetry maps

Maxime Ballarotta (CLS, France)


Clement Ubelmann (CLS, France); Marie-Isabelle Pujol (CLS, France); Guillaume Taburet (CLS, France); Florent Fournier (CLS, France); Jean-Francois Legeais (CLS, France); Yannice Faugère (CLS, France); Antoine Delepoulle (CLS, France); Dudley Chelton (Oregon State University, USA); Gerald Dibarboure (CNES, France); Nicolas Picot (CNES, France)

Event: 2018 Ocean Surface Topography Science Team Meeting

Session: Quantifying Errors and Uncertainties in Altimetry data

Presentation type: Type Poster

The DUACS system produces multi-mission altimetry sea level global and regional maps that serve oceanographic applications, climate forecasting centers, geophysic and biology communities. These maps are constructed from optimal interpolation of along-track altimetric observations and are provided on a global regular ¼°x ¼° (longitude x latitude) and daily resolution framework through the Copernicus - Marine environment monitoring service. Yet, the dynamical content of these maps is not ensured to have a full ¼° spatial and 1-day resolution, due to the filtering property of the optimal interpolation.

Several studies showed that altimeter along-track resolves scales in the order of few tens of kilometers (Dussurget et al., 2011, Dufau et al. 2016). We here propose to examine the resolution of the maps produced from the merging of these along-track altimeter data and hence deliver to the users the resolving capabilities of the maps.

After introducing the newly reprocessed delayed-time DUACS maps (aka, DUACS-DT2018), we will present the methodology to estimate the "effective" spatial and temporal resolutions and its application to the DUACS-DT2018 dataset. We show that the spatial resolution of the DUACS-DT2018 global maps ranges from ~100km at high latitude to ~800km in the Equatorial band and the mean temporal resolution is ~28 days. In other word, the DUACS-DT2018 maps resolve mesoscale structures of 50 to 400 km diameter over 4 weeks' time scale. The mean effective spatial resolution is estimated ~120 km for the regional Mediterranean Sea product and ~140 km for the regional Black Sea product.

Comparisons with the former DUACS reprocessing (DUACS-DT2008, DUACS-DT2010, DUACS-DT2014) highlight the evolution of the gridded product resolution, becoming globally finer (resolution gain > 10%) upgrade after upgrade. The same diagnostic applied to maps constructed with one altimeter, maps with two altimeters and maps with three altimeters confirms the increase of resolving capabilities in the DUACS maps with the number of mission.

Poster show times:

Room Start Date End Date
Foyer, Salao Nobre & tent Thu, Sep 27 2018,18:00 Thu, Sep 27 2018,20:00
Foyer, Salao Nobre & tent Fri, Sep 28 2018,14:00 Fri, Sep 28 2018,15:00
Maxime Ballarotta