Carbon Explorers Fly SOLO
SOLO floats ("sounding oceanographic Lagrangian observers"), invented by Russ Davis of the Scripps Institution of Oceanography, can be programmed to descend as deep as 2,000 meters to measure temperature and salinity, then resurface to send their data to satellites overhead.
Seeing the potential of SOLOs as robotic carbon observers, Jim Bishop and his colleagues devised instruments that SOLOs could use to measure organic carbon particles like plankton and inorganic particles like calcite, the most common carbon mineral in seawater.
By installing advanced two-way telemetry, Bishop's group made it possible for SOLOs to transmit more data at a faster rate.
Researchers were also able to reprogram diving schedules remotely.
Since wind and waves often make it impossible to contact communications satellites, the floats can store several days' worth of data and play it back later. "SOLO floats are designed to operate in all weather conditions," says Bishop. "They fly in the oceans as balloons fly in the air, for seasons at a time."
The first operational SOLO carbon explorers were launched at Ocean Station PAPA , in tempestuous North Pacific waters a thousand miles west of Vancouver Island, in April, 2001; over eight months later they were still reporting, "tracking the daily rhythm of the plankton." A more advanced version was "torture-tested" in rough California coastal waters that summer.
A much tougher test came in the winter of 2002, when four SOLOs were deployed during the SOFeX experiment to test the "iron hypothesis" in the Southern Ocean, the stormiest place on the planet. The result: unexpected discoveries and major savings of costly ship time, through pinpoint tracking of patches of fertilized plankton growth.