CMEMS WAVE-TAC, Recent upgrades and enrichment of the satellite constellation for near-real-time ocean waves characterization

Elodie Charles (CLS, France)

CoAuthors

Romain Husson (CLS, France); Alexis Mouche (IFREMER, France); Annabelle Ollivier (CLS, France)

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

Session: Application development for Operations

Presentation type: Type Forum

A near-real-time wave service started in July 2017 in the frame of the Copernicus Marine Environment Monitoring Service (CMEMS). Handled by the WAVE-TAC (Thematic Assembly Center), a partnership between CLS and IFREMER, it provides near-real-time wave products derived from altimetry and SAR measurements.

Based on the Level-2 nadir products, the 1Hz along-track Level-3 significant wave heights (SWH) are processed and distributed on CMEMS catalogue. This year, two new satellites joined the 5-satellite operational constellation. CFOSAT SWIM nadir in February 2020, and HaiYang-2B in July 2020. In addition, a major upgrade was carried out to include the altimetry wind speed in July 2020.

The daily gridded Level-4 SWH product is now merging wave heights derived from 7 different missions: Jason-3, Sentinel-3A, Sentinel-3B, SARAL/AltiKa, CryoSAT-2, CFOSAT, and HaiYang-2B. The increased spatial and temporal density of measurements allows a better mapping of the wave heights. Furthermore, a new mapping method for the instantaneous estimate of SWH (VAVH_INST) will be launched for CMEMS December 2020 version.

Level-3 wave spectral parameters (SPC) products are based on the Level-2 Sentinel-1A and -1B directional wave spectra. From the integral parameters estimated for each wave partition (significant wave height, peak period and peak direction), wave observations are gathered according to the swell field they belong to. This is based on back-propagation in space and time using great circle theory: wave measurements converge to their storm source. This association in swell fields enables filtering out wave observations inconsistent with respect to the overall swell distribution. In July 2019, the operational chain was upgraded to better characterize long swell measurements and to propose an additional 3-hourly format. The CFOSAT mission will soon join the L3 SPC operational constellation, providing wave spectral parameters derived from the SWIM off-nadir instrument.
Finally, a new Level-4 gridded spectral product will be added at the end of 2020, providing maps of intercalibrated and merged Sentinel-1A and -1B spectral wave parameters.

This presentation will describe the processing, the characteristics, and the validation of these different wave product upgrades, suitable for several applications such as NRT assimilation in numerical wave models, the study of swell dissipation or wave/current interactions.
 
Elodie Charles
CLS
France
echarles@groupcls.com