Evaluation of the Carbon Wave Glider as a Tool for Scientific Studies

Along the Pacific coast of the United States, dynamic natural processes cause meso-scale spatial (kilometers) and temporal (days to months) variability in carbon dioxide (CO₂) at the air-sea interface. Understanding natural coastal carbon cycling is further complicated by the ocean’s role as a sink for anthropogenic CO₂. Annual or biannual survey cruises and anchored moorings are currently used to evaluate coastal carbon dynamics, but the data suggest that they inadequately capture the spatio-temporal variability. To address this concern the Pacific Marine Environmental Laboratory (PMEL) Carbon Program integrated biogeochemical sensors into a new autonomous platform, a carbon wave glider. In 2011 and 2012 (July-September 2011 and July-October 2012) two carbon wave gliders were deployed along the Washington and Oregon coastlines. The validity of the new wave glider CO₂ sensors was verified using comparisons to concurrent measurements from coastal moorings and research cruises. Analyses of the wave glider CO₂ data revealed significant CO₂ concentration changes over one to two kilometers and over time-scales of a few days. These results suggest that autonomous platforms, like the carbon wave glider, may be required in addition to moorings and survey cruises to effectively characterize the spatio-temporal variations within the highly dynamic coastal carbon system.