Profiling Float

A profiling float is a subsurface autonomous instrument that cycles vertically by changing buoyancy, measuring a water-column profile on each ascent. The Argo float, the dominant type, parks at 1000 m for about 9 days, sinks to 2000 m, then rises while sampling conductivity, temperature, and pressure, transmitting over Iridium at the surface before re-sinking on a roughly 10-day cycle. The Argo array holds near 4000 floats and passed its three-millionth profile in July 2024. Biogeochemical Argo floats add oxygen, nitrate, pH, chlorophyll, and irradiance. Floats give the global subsurface temperature and salinity coverage that ships and moorings cannot, and they anchor ocean reanalyses.