First Automated Floats For Monitoring Ocean Carbon Launched In North Pacific

Todd Wood of the Department of Energy's Lawrence Berkeley National Laboratory carried the SOLOs to the Polar Star by helicopter from Dutch Harbor in the Aleutian Islands. At 3:00 a.m. Tuesday Wood deployed the floats at Ocean Station PAPA, 1,000 miles west of Vancouver Island, British Columbia, with the help of US Coast Guard personnel.

On Wednesday morning, April 11 they had resurfaced and had begun returning data by satellite link. Contact was interrupted by high waves during North Pacific storms Thursday and Friday, but no data was lost, and by Saturday transmissions from both float were being received regularly.

Invented by Russ Davis of the Scripps Institution of Oceanography in La Jolla, Calif., who dubbed them SOLO (for Sounding Oceanographic Lagrangian Observer), the floats incorporate new carbon biomass sensors and also measure temperature, salinity and mid-depth currents. From the surface they descend a thousand meters (a quarter of the way to the sea floor) and resurface at dawn and dusk each day.

Each time they surface the floats communicate their collected data, along with their positions, by two-way telemetry link to ORBCOMM satellites. For optimal data collection, the new bidirectional telemetry system allows land-based scientists to control the up and down motion of the floats anywhere in the remote ocean for the first time.

"This concept experiment will pave the way for a fully instrumented SOLO-carbon observer, able to measure all components of carbon in seawater," says Jim Bishop, director of the Ocean Biogeochemical Processes Group in Berkeley Lab's Earth Sciences Division. Bishop spearheaded the concept of robotic profiling carbon sensors and leads the collaboration that built and instrumented the floats and is collecting their data.

"We chose to deploy the floats at Ocean Station PAPA," he explains, "because our group has worked there extensively and because our colleagues at the Institute of Ocean Sciences in British Columbia regularly visit PAPA by ship. This way we can make sure we get consistent answers, in a place we understand."

A third of the carbon currently emitted by human activity -- roughly two billion metric tons each year -- is absorbed in the oceans, but the process is not well understood. The SOLO floats are vital, says Bishop, "because the plants that fix carbon in the ocean typically live and die in a single day. This makes it really hard and expensive to follow their variability using a ship. When the weather gets bad all work on a ship has to stop, yet biology goes on unobserved."

And the weather does get bad. Last week, in the aftermath of the worst storm in the North Pacific in decades, the Polar Star was involved in the search for a fishing boat that went down in the Bering Sea with the loss of all 15 aboard. "This tragedy," says Bishop, "underscores the difficulty and danger inherent in making observations at sea." The SOLO floats are designed to operate in all weather conditions, and "they fly in the ocean as balloons fly in the air, for seasons at a time, tracking the daily rhythm of the plankton."

###Partners in the SOLO-carbon venture include the Instrument Design Group at Scripps and WET Labs, Inc., of Philomath, Oregon, a private instrument firm. Support for the collaboration is provided by the National Oceanographic Partnership Program (NOPP), the Department of Energy, and the National Oceanic and Atmospheric Administrations's Office of Global Programs. There are plans to launch two more SOLO-carbon observers in the North Atlantic later this year.

The Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California. Visit our website at http://www.lbl.gov.