Copernicus Marine Service
OC-TAC - Quality Control and Validation

Common metrics (see Table 1) have been adopted by the PUs of the OC TAC. These metrics are applied to all variables (see Table 2) distributed by the OC TAC.

Due to the non-availability of NRT in situ data, the product quality control is determined in terms of the satellite observations’ temporal consistency through the use of climatological satellite data.
Full description of the ScVP is available here.

Name Description Ocean Parameter Supporting reference dataset Quantity
SURF-D-CLASS1-CLIM-NDIFF Difference between observations and climatology see Table 2 climatology, see Table 3 Difference between daily observations and climatology. The difference is then divided by the standard deviation of the climatology. The result is an indicator usually bounding in the range [-4, +4]. This indicator is computed at pixel level on the daily NRT product.
SURF-D-CLASS1-CLIM-HISTO Distribution of the OC-DIFF CLIMATO QI. see Table 2 An histogram is computed based on the OC-DIFF-CLIMATO indicator. The pixels considered are all the valid pixels available on the considered region (GLO, MED, BS, ARC, BAL, ATL) for a given day.
SURF-D-NC-CLIM-AVAIL Number of valid pixel in an image see Table 2 Number of valid pixels on the considered region (GLO, MED, BS, ARC, BAL, ATL) for a given day. This number varies mainly due to clouds or seasonal condition (e.g., darkness during polar winters).
Table 1: list of metrics

Ocean Variables PU
RRS(λ): normalized remote sensing reflectance ACRI, CNR, PML
CHL: Chlorophyll-a concentration (Chla) ACRI, CNR, PML
KD: diffuse attenuation coefficient at 490 nm ACRI, CNR, PML
BBP: particulate backscattering coef. at 443 or 555/547 nm ACRI
APH: absorption coef. due to phytoplankton at 443 nm PML
ADG: absorption coef. due to cdom and non-pigmented particles at 443 nm ACRI, PML
ATOT: total absorption coef. PML
ZSD: Secchi depth ACRI
SPM: non organic Suspended Matter ACRI, PML
Table 2: Variables monitored by the OC TAC for PQ.

PU Climatology inputs Resolution of the climatology Period Products
ACRI Copernicus-GlobColour R2018 (merged SeaWiFs, MERIS, MODIS, VIIRS) 4km at Global Level
1km at European level
1998-2017 All
CNR SeaWiFs 1km 1997-2010 All
PML SeaWiFs 4km 1997-2011 all single-sensor regional products except OC5CI
PML CCIv3 (merged SeaWiFS, MERIS, MODIS, VIIRS) 1km 1997-2015 all multiple-sensor products (RRS & OC5CI) + single-sensor regional OC5CI
Table 3: Climatology used by the PUs: each PU uses its own climatology with own characteristics (period, resolution, algorithm).