This document is the Drifter quality control manual. It is derived from Argo floats quality control on trajectories (http://dx.doi.org/10.13155/33951).

Changes from the previous version of the manual are highlighted in yellow.

The Drifter data system has three levels of quality control.

• The first level is the real-time system that performs a set of agreed automatic checks on all drifter measurements. Real-time data with assigned quality flags are available to users within the 24-48 hrs timeframe.
• The second level of quality control is the delayed-mode system.
• The third level of quality control is regional scientific analyses of all drifter data with other available data. The procedures for regional analyses are still to be determined.

This document contains the description of the Drifter real-time and delayed-mode procedures.