Real Time Quality Control of biogeochemical measurements.Version 2.5. [MyOcean WP.15]

The present version includes a more detailed description of challenges and difficulties related to real -time data quality control (RTQC) from biogeochemical (BGC) sensors as opposed to data from physical sensors has been added to this document (Section 2). The main goal of adding this information is to help the reader to understand the possibilities and limitations regarding RTQC of BGC data. For instance, there is a need to clearly distinct between bad Chlorophylla (Chl a) data caused by sensor failure and uncertain data caused by inherent natural variations in the Chl a fluorescence:Chl a concentration ratio. An extra paragraph addressing this issue has also been included in Section 1. Further progress of the current document will include a refined and extended set of real-time quality tests that can realistically be established to work on BGC data from various in situ platforms. Additions are under development and will be provided in Section 4. The following tests are under consideration for revision: Gradient/ spike test; Range test (global + regional) ; Inter-sensor comparison ; Vertical range test; Biofouling detection test ; Parameter relationship test; Oxygen vs Chl a fluorescence ; T/S vs fluorescence ; Day/night; ;sun height The revised tests should be applied on a selected dataset in order to assess their validity. These revisions provide also a better roadmap for delayed mode quality control procedures. . Published Refereed Current Standard Operating Procedure Guide