Sentinel-3 Chlorophyll-a reprocessing

Sentinel-3 Chlorophyll-a Near Real Time (NRT) data have been missing on Creodias for several time ranges earlier this year, notably between 28th April and 9th June 2023.

After several months of wait and long discussions with the support team, it has been deemed impossible to get these NRT data in a timely manner.
Leaving a large gap in the temporal coverage available in Syntool portals would not be satisfying, so we decided to use the Non Time Critical (NTC) version of these data as these are available on Creodias.

Having a mix of NRT and NTC data displayed together on the map could introduce visual artifacts and discontinuities that do not reflect any physical phenomenon, and therefore be a source of confusion.

To limit the mix of the two versions, we chose to replace the NRT with the NTC results from the end of our last reprocessing (1st February 2022) until the end of July 2023 (the last missing NRT file was on 19th July 2023).
That way there is not a day containing both NRT and NTC data, the time ranges for each version are clearly defined:
  • From April 2018 to 31st December 2020: NRT
  • Between 1st January 2021 and 31st July 2023: NTC
  • From 1st August 2023 onward: NRT

Sentinel-3 Chlorophyll-a from the L2 NTC data produced by Eumetsat (

CMEMS update

On 30th November CMEMS updated several products that we process automatically and include in Syntool portals. A short description of the changes that could make the new data look different than the ones we processed so far (due to algorithm changes, additional input data and other sources of quality improvements) is available below.

Geostrophic current + NRT maps of SSH & SLA
Starting 1st December 2023, the geostrophic surface current ( rendered as streamlines in Syntool, the SSH map ( and the SLA map ( will use the new product distributed by CMEMS.

According to the CMEMS update description, the changes are:

  • * Use of L3 5Hz data for mapping Moreover, the input products to the calculation of the L4 products will evolve: the L3 1Hz product, historically used, will be replaced by the 5Hz version when it is available. The expected impact is a slight improvement of the L4 product quality, especially in areas where L3 5Hz availability is better than the 1Hz version.
  • * New mission SWOT-Nadir The measurements from the new mission SWOT-Nadir will be used in L4 GLO/EUR processing in addition to other active missions, resulting in improved product quality.

Total current
Starting 1st December 2023, total surface current ( and total current at 15m ( rendered as streamlines in Syntool will use the new product distributed by CMEMS.

The most notable change is the switch to a finer temporal resolution (from 6-hourly to hourly).

MFWAM wave analysis and forecast
Starting 1st December 2023, the visualisation of variables from wave analysis and forecast will be based on the new version of the product distributed by CMEMS.

In Syntool portals the following products are impacted:

Relevant changes from the CMEMS update description:

  • * Upgrade wave model to IFS-ECWAM 47.R2 version
  • * Use of 6-hourly currents forcing (Upstream data change)
  • * Assess GLO12V4 current data compared to GLO12V3 (Upstream data change)
  • * HY2B & HY2C assimilation (Upstream data change)

New products

OSI-SAF sea ice concentration
Three NRT sea ice concentration products distributed by OSI-SAF have been added near the end of October:

SWOT-Nadir NRT SWH & Wind speed
In addition to improvements on existing products, yesterday's CMEMS update brought a new dataset for NRT significant wave height and wind speed from SWOT nadir measurements.

3 days of SWOT nadir NRT significant wave height (
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