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
CHL: Chlorophyll-a concentration (Chla)	ACRI, CNR
KD: diffuse attenuation coefficient at 490 nm	ACRI, CNR
BBP: particulate backscattering coef. at 443 or 555/547 nm	ACRI
APH: absorption coef. due to phytoplankton at 443 nm	CNR
ADG: absorption coef. due to cdom and non-pigmented particles at 443 nm	ACRI, CNR
ZSD: Secchi depth	ACRI
SPM: non organic Suspended Matter	ACRI

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

Table 3: Climatology used by the PUs: each PU uses its own climatology with own characteristics (period, resolution, algorithm).