Argo Float Network for Hydrography

The Argo array is a global fleet of about 4,000 autonomous profiling floats that measure temperature, salinity, and pressure over the upper 2,000 m of the ocean, first deployed in 2000. Each float runs a ten-day park-and-profile cycle: it sinks to a 1,000 m drift depth, parks nine days, descends to 2,000 m, then profiles with a CTD sensor as it rises and transmits by satellite at the surface. The design spaces roughly one float per 3-degree box, giving a profile every ten days worldwide. Argo data anchor ocean heat content, the steric component of sea-level rise, and the hydrographic reanalyses that tide-gauge and altimeter records are checked against.