BGC-Argo quality control manual for nitrate concentration

This document is the Argo quality control (QC) manual for nitrate concentration, where the metadata parameter name for the state variable is NITRATE with units μmol kg-1. The document describes two levels of quality control: - The first level is the “real-time” (RT) quality control system, which always includes a set of agreed-upon automatic quality-control tests on each measurement. Data adjustments can also be applied within the real-time system, and quality flags assigned accordingly. - The second level is the “delayed-mode” (DM) quality control system where data quality is assessed in detail by a delayed-mode operator and adjustments (based on comparison to high-quality reference fields) are derived. As mentioned, these adjustments can then be propagated forward and applied to incoming data in real-time until the next delayed-mode assessment is performed.