Sentinel-3 Recommended Flags

SNAP generates for OLCI Level-2 data a set of recommended flags. Those flags are defined by an group of experts, named the Sentinel-3 Quality Working Group (S3-QWG). This group observes and analyses the data and suggests means to ESA and Eumetsat to maintain high quality data.
For building temporal or spatial synthesis, or working in unsupervised mode, it is recommended that the users exclude pixels which are flagged by at least one of the following flags, to exclude unreliable pixels for the individual products.

For Land and for Water level-2 products different sets of flags have been defined. They combine already the existing LQSF/WQSF flags to a new flag. Where LQSF and WQSF stand for Land/Water Quality and Science Flags. The intention is to ensure good data quality when using/processing the Level-2 data. In SNAP they are displayed as masks in the Product Explorer and in the Mask manager.

Recommended Water Flags

The following recommend flags are defined for the Water products:

WQSF_REFLECTANCE_RECOM
WQSF_CHL_OC4ME_RECOM
WQSF_KD490_M07_RECOM
WQSF_PAR_RECOM
WQSF_W_AER_RECOM
WQSF_CHL_NN_RECOM
WQSF_TSM_NN_RECOM
WQSF_ADG443_NN_RECOM
WQSF_IWV_NN_RECOM

The flags identify pixels not suitable for usage in water products.

Detailed information can be obtained from the product notice published on the Eumetsat website:
S3 Product Notice - OLCI (S3.PN-OLCI-L2L.03 - 23/06/2020)

The flag LQSF_IWV_RECOM has been added in addition to the product notice. It is defined like the LQSF_GENERAL_RECOM plus the LQSF.WV_FAIL flag.