MERCATOR OCEAN JOURNA: 
SEPTEMBER 2021 
1.3 Toward more wave parameters 
SAR measurements are processed in a single type of product: 
Level-3 SPC. It consists in both along-track and along swell- 
oath wave integral parameters, derived from Sentinel-1A and 
-1B missions. The dataset parameters include partition SWH, 
partition peak period and partition peak or principal direction 
given along swell propagation path in space and time at a 
3-hour timestep, from source to land. 
This product is proposed in two different formats: 
öbservations grouped according to the initial storm event 
they originate from or grouped in 3-hour files according to 
their observation time. This last format was introduced in 
2019 as required by numerical wave modelers for data 
assimilation. 
In 2019, a better characterization of long swell was also 
introduced in the Level-3 processing to deal with the 
Level-2 inherited inability to properly estimate the swel. 
propagation direction for the longest swell systems. 
An important work was also initiated to integrate spectral 
parameters derived from CFOSAT off-nadir SWIM instrument. 
This new Level-3 dataset should become operational to all 
users in 2021. This new source of data will complement the 
Sentinel-1 mission already existing products by providing 
swell observations on all ocean basins, including North 
Atlantic, and with different limitations than those of SAR 
(especially shortest and azimuth propagating swells). This 
will be the first inclusion of measurements from another 
mission concept in the L3 SPC products, which will require a 
careful intercomparison and inter-calibration. 
2. STATUS AT THE END OF COPERNICUS 1 
At the end of Copernicus 1, the WAVE-TAC is delivering three 
NRT wave products (see Figure 2), including SWH and spectral 
parameters, derived from a constellation of nine satellites. 
The spatio-temporal coverage of the Level-3 SWH product 
was significantly increased with the integration of a total of 
7 altimeters, including the Copernicus Sentinel-3A/B 
‚nterleaved missions. Only valid measurements are 
jisseminated, and the consistency between measurements 
ıs guaranteed by the cross-calibration onto the reference 
mission (Jason-3) and onto in-situ measurements. NRT 
Jata are usually available 3 to 4 hours after the actuaı 
acquisition, enabling their assimilation in forecasting 
systems. Also, the high number of qualified measurements 
and associated wind field directly benefit wave simulations 
and ensure an increased resilience of the system when a 
mission Is temporarily unavallable. 
The gridded Level-4 SWH product also benefited from the 
high number of Level-3 measurements and provides user- 
friendly maps, containing different daily statistics and an 
instantaneous estimate of the mid-day wave height field 
The Level-3 SPC product based on Sentinel-1’s constellation 
currently delivers partitioned wave spectra at observation 
time as well as integral parameters (partition significant 
wave height, partition peak period and partition peak or 
orincipal direction) given along swell propagation path in 
space and time at a 3-hour timestep, from source to land. 
Quality flags are also included for each parameter and 
indicate the valid time steps along propagation (e.g., no 
propagation for SWH close to a storm source or any integraı 
parameter when reaching the land). The integral parameters 
at observation points are also available together with a 
quality flag based on the consistency between each 
propagated observation and the overall swell field. 
Since the creation of the WAVE-TAC, the quality and quantity 
of data has been continuously improved. New fields (quality 
flags, uncertainty, wind speed) were added to match evolving 
user's needs. The validation approach was reinforced by 
zomparing satellite measurements not only with other 
satellites, but also with in-situ measurements and simulation 
autputs. Facilitating the uptake of Copernicus Marine Service 
Wave products is essential for a broader utilization by both 
internal and external users. Along-track altimeter and SAR 
products are well known In the assimilation community, but 
their spatio-temporal sampling requires some expertise for 
new users. Therefore, the WAVE-TAC took the opportunity to 
zommunicate on the wave products and their evolution and 
Juality at international scientific conferences and during a 
dedicated Wave Group / TWAPAS (Tailored WAve Products 
for Assimilation Systems) meeting