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13 September 2018 at 11:09 #1250blovedayModerator
Current status of S3A:
OLCI-A performance is nominal, continuing to operate within expected parameters. Brief anomalies with cameras 2 and 5 occurred on June 21st and July 13th, respectively. More information on the timing of the anomalies can be accessed via the EUMETSAT user notification service: https://uns.eumetsat.int/
Current status of S3B:
OLCI-B is in the Commissioning Phase. It has completed the LEOP and SIOV phases and has been flying in tandem with OLCI-A since June 6th. This configuration will persist until October, when the commissioning phase will end, and the OLCI-B instrument will begin its drift to its final orbit, 140 degrees out of phase with OLCI-A.
Preliminary analysis of OLCI-B suggests that it is more similar to MERIS than OLCI-A with respect to top-of-atmosphere radiance. Initial inspection suggests that radiometric performance is stable and within the mission requirements, except for the band Oa21. Geolocation is slowly drifting for some cameras outside the mission specifications and recalibration will be available to bring error statistics in line with OLCI-A.
Initial evaluation of OLCI-B Level-2 ocean colour products is on-going. OLCI-B System Vicarious Calibration (SVC) is not yet available, so biases in radiometric and derived products are expected.
Comparison of the standard open-water level-2 chlorophyll product with the analogous OLCI-A and OC3 VIIRS products suggests that;
For the oligotrophic gyres: [Chla] OLCI-A < [Chla] OLCI-B < VIIRS
For turbid waters: VIIRS < [Chla] OLCI-B < [Chla] OLCI-A
OLCI-B appears to be 5-18% brighter in the blue/green and up to 50% brighter in the red.
In future operational processing, the CHL_NN Chlorophyll product will switch to using an alternative neural network, which shows improved performance in optically complex waters. The alternative neural network files are currently available through S3VT and can be used via the SNAP C2RCC processor. The new ‘Cloud Risk’ flag for complex water neural network products will also be introduced.
Future processing will bring improvements in the bright pixel correction (BPC) for open waters and introduction of the chlorophyll index algorithm (Hu et al., 2012) for oligotrophic gyres (where OLCI currently underestimates). Also, band 10 (681 nm) smile correction will be implemented.
Additional work is underway to:
- Develop new IOP products
- Develop new fluorescence product
L1B and L2 marine products for OLCI-B have been released to the Sentinel-3 Validation Team. Full and reduced resolution, NRT and NTC products are available. For any issues with data access associated with S3VT, please contact the EUMETSAT help desk at firstname.lastname@example.org.
Users should be aware that:
- instrument characteristics are not finalised and changes may still occur
- Data flow is not continuous
- SVC gains ARE NOT applied to OLCI-B Level-2 products, gains are set to 1, – this will affect both radiometry and derived products.
- Product notices for the L1 and L2 products should be consulted prior to use.
- We would kindly request not to base or release any publication, web stories, etc on these pre-operational sample products.
For more information on S3VT activities across all Sentinel-3 sensors, keep an eye on the EUMETSAT news stream. For any non-S3VT members who are interested in joining the validation team, you can this via application to the rolling S3VT call, here:
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