Drifting Buoy

A drifting buoy is a free-floating, unmoored buoy that follows surface currents while reporting sea surface temperature, sea level pressure, and position. The standard Surface Velocity Program drifter pairs a small surface float with a holey-sock drogue centered at 15 m, so the buoy tracks the 15 m current rather than wind and waves. Position fixes from GPS and the Argos system give surface velocity; the barometer feeds marine weather analysis. The Global Drifter Program keeps roughly 1300 drifters active across the world ocean, the backbone of in-situ SST that calibrates satellite radiometers and anchors current climatologies.