A global reprocessing of Argo chlorophyll-a (CHLA) observations is currently underway across the Biogeochemical Argo network. Initiated on 8 June 2026, this effort aims to improve the consistency and quality of chlorophyll-a measurements distributed through the international Argo data system and subsequently used in Copernicus Marine products.
The progress of the reprocessing can be monitored in near real time through the dedicated webpage: Biogeochemical Argo | CHLA Reprocessing – Updates & Resources .
As part of this transition, Copernicus Marine In Situ TAC will implement a temporary quality-control measure in its MYNRT biogeochemical products. Starting on 8 July 2026, chlorophyll-a observations originating from Argo floats that have not yet been reprocessed by their Data Assembly Centre (DAC) will be assigned the quality flag QC3 (doubtful data, potentially correctable).
This approach follows recommendations from the BGC-Argo community regarding real-time unadjusted chlorophyll-a observations. Chlorophyll-a concentrations derived from fluorometer measurements are known to be affected by several factors, including sensor calibration uncertainties, dark-signal estimation, fluorescence quenching and sensor drift. These effects can often be corrected through real-time and delayed-mode scientific processing and expert quality control.
The temporary QC3 flag therefore does not indicate that the observations are erroneous or unusable. Rather, it identifies measurements that have not yet benefited from the ongoing chlorophyll-a reprocessing and should consequently be used with appropriate caution until the updated data become available.
This measure has been implemented in close collaboration with the Argo BGC data management team to provide users with clear information on the processing status of chlorophyll-a observations during the reprocessing campaign while maintaining access to the full dataset.
Users are encouraged to consult the quality flags associated with chlorophyll-a observations and to follow the dedicated reprocessing webpage for the latest updates on the progress of the campaign.
