For more than 20 years, about 4,000 autonomous profiling floats have been drifting through the ocean. They form part of the international Argo program (Argo—global array of profiling floats). At regular intervals, they descend to a depth of 2,000 meters (6,600 feet) and, as they rise, measure para meters such as temperature, salinity and pressure. Once they reach the sea surface again, they transmit these data via satellite to the Argo network, which is available to researchers worldwide. Hardly any other observation system has transformed ocean research so profoundly in recent decades. ...read more read less