High frequency observations are critical for characterizing the natural variability and secular trends in the ocean carbon cycle.
Ocean carbon measurements have shown significant biogeochemical variability over a wide range of timescales from sub-diurnal to decadal periods. In situ measurements are also providing a growing body of evidence that episodic phenomena are extremely important causes of variability in CO2 and related biogeochemical properties. Time-series records are essential for characterizing the natural variability and secular trends in the ocean carbon cycle and for determining the physical and biological mechanisms controlling the system. The biological and chemical responses to natural perturbations (e.g., El Niño/Southern Oscillation, dust deposition events) are particularly important with regard to evaluating potential responses to anthropogenic forcing and for evaluating the prognostic models used in future climate projections. Ship-based time-series measurements are impractical for routinely measuring variability over intervals from a week to a month, they cannot be made during storms or high-sea conditions, and they are too expensive for remote locations. Instrumental advances over the past 15 years have led to autonomous moorings capable of sampling properties of chemical, biological, and physical interest with resolutions as good as a minute and duty cycles of a year or more. Although these new technologies are still underutilized, they have been identified as a critical component of the global ocean observing system for climate.
The primary mission of this project is to evaluate the variability in air-sea CO2 fluxes by conducting high resolution time-series measurements of atmospheric boundary layer and surface ocean CO2 partial pressure (pCO2).
In 2004, the moored CO2 program was initiated by the Climate Program Office (CPO) as part of the Global Ocean Observing System. To initiate the development of a global moored CO2 network, the PMEL carbon group worked with researchers at the Monterey Bay Aquarium Research Institute (MBARI) to transfer the technology for a moored pCO2 system MBARI had developed for buoys in the Equatorial Pacific. Over the next 5 years the PMEL carbon group worked to make the PMEL moored pCO2 systems (called MAPCO2) more accurate, more reliable and easier to deploy. The MAPCO2 systems collect CO2 data from surface seawater and marine boundary air every three hours for up to a year at a time before they need servicing. Daily summary files of the measurements are transmitted back to PMEL where the data are examined and plots of the results are posted to the web in near-real time. In 2009 the MAPCO2 technology was transferred to Battelle Memorial Institute to be commercially produced so the systems will be more accessible to the larger scientific community.
Today, the PMEL carbon group operates dozens of MAPCO2 systems in the Pacific, Atlantic, and Indian oceans in collaboration with a wide range of partners. The types of sites we are studying generally fall into three categories: Open Ocean, Coastal, and Coral Reef. See the descriptions of each below.