A sketch of a modern ocean drifter. The surface float has instruments to measure air pressure, sun light level and sea surface temperature (SST) and a sensor to indicate whether the float is pushed under by strong waves. The sea anchor is a 15 m long tube of 1 m diameter with a series of holes (the "holey-sock drogue"). At the top of the drogue is a mini-CTD. The data are transmitted to shore via satellite.
The photos below show a drifter laid out on land before deployment and just after deployment from a ship.
© 2000 Atlantic Oceanographic and Meteorological Laboratory of the National Oceanic and Atmospheric Administration (AOML/NOAA), reproduced by permission
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