Toward Higher resolution Level-3 altimeter products

Marie Isabelle Pujol (CLS, France)

CoAuthors

Yannice Faugere (CLS, France); Stephanie Dupuy (CLS, France); Oscar Vergara (CLS, France); Quentin Dagneaux (CLS, France); Mei-Ling Dabat (CLS, France); Gerald Dibarboure (CNES, France); Nicolas Picot (CNES, France)

Event: 2020 Ocean Surface Topography Science Team Meeting (virtual)

Session: Application development for Operations

Presentation type: Type Forum

The DUACS system (Data Unification and Altimeter Combination System) produces, as part of the CNES/SALP project, and the Copernicus Marine Environment and Monitoring Service (CMEMS), high quality multi-mission altimetry Sea Level products for oceanographic applications, climate forecasting centers, geophysic and biology communities. These products consist in directly usable and easy to manipulate Level 3 (along-track cross-calibrated SLA) and Level 4 products (multiple sensors merged as maps or time series). They are widely used for different applications, including assimilation in numerical models.
With the future altimeter missions as the large swath SWOT mission, the altimeter processing will face a new challenge: be able to accurately process the signal at finer spatial scales. On the other hand, users and more particularly modelers need to make their system ready for assimilation and propagation of the finer scale structures observed. Additionally, observation of the coastal area remains a challenge for the conventional altimeter measurement.
But new techniques and processing now allow to significantly reduce the measurement errors and noises, essential step to pretend observe the small mesoscale structure with the nadir altimeter measurement. A new generation of Level-3 along-track products is under development with support from CNES. They are derived from high resolution (20Hz) altimeter measurement and are specifically processed in order to better solve finer scales up to ~30 km. They merge recent developments that enable to optimize the Sentinel3 SAR altimeter processing (Boy 2017, Moreau,2020) and the Jason noise level (Thibaud et al, 2017; Poisson et al, 2018, Tran 2019) and allow us to better exploit the fine-scale content of the altimetric missions. They also take into account improvements that are also done in geophysical corrections estimation (e.g. internal tide model [Zaron 2018]) and local Mean Sea Surface Estimation (e.g. Dibarboure et Pujol, 2019). Experimental datasets, with a nearly 1km (5Hz) sampling, are already available on AVISO+ (https://www.aviso.altimetry.fr/duacs) and can be tested by users. We will present these experimental 5Hz products defined over the Europe region, including part of the North Atlantic, the Baltic, Mediterranean and Black Sea.
The processing algorithm, here studied in R&D context, could be implemented in a future version of the operational L2p/L3 altimeter production for Eumetsat/CMEMS.
 
Marie Isabelle Pujol
CLS
France
mpujol@groupcls.com