The PIs request funding to complete the development of the Carbon Flux Explorer (CFE), a fully autonomous and free robotic system designed to measure and relay in real time via Iridium satellite link the hourly/diurnal variations of particulate organic carbon (POC) and particulate inorganic carbon (PIC) flux at various depths in the upper kilometer of the ocean for seasons to year-long time scales. CFEs are the successful integration of the Sounding Oceanographic Lagrangian Observer (SOLO) float (developed at Scripps) and LBNL/UC Berkeley?s imaging Optical Sediment Trap (OST). The first prototype CFE was successfully tested at sea for 2 days to 800 m in June 2007.
The proposed new work will refine and challenge the CFE design with successively longer deployments in coastal and California Current waters to evaluate and address real world issues such as biofouling and animal invasions. At the same time, engineering refinements will improve power budget and solve multiple minor system issues. On-board image processing/data reduction software will be fully established. Calibration samples (POC and PIC flux) will be obtained concurrently with CFE testing using a buoy tethered twinned OST system operating at similar depths. At the end of this project, three fully developed Carbon Flux Explorers (CFEs) will be deployed (and recovered if possible) in the open ocean for at least 3-6 months in the subarctic N Pacific.
Carbon sedimentation via the bio-carbon pump of the ocean is important to the regulation of atmospheric CO2. Due to limitations of current observational methodology (moorings/ships), carbon export (or sedimentation) is poorly observed in space and time and therefore is poorly understood and parameterized in carbon cycle simulations. CFE deployments in the world?s ocean have the potential to lead to fundamentally new insights into the biology/biogeochemistry of carbon sedimentation.
Broader Impacts:
The potential benefits to society due to the proposed activities are important. These actives will help improve confidence in future carbon cycle predictions. The results could maybe a key to helping society deal with the potentially economically and environmentally hazardous consequences due to climate change. Through education, the proposed activities and technologies developed will make the ocean more accessible to the public in general. An improved understanding of the ocean by the public will help protect the ocean's environment. The real-time observations offered by the proposed activities will help bring about such an understanding and diminish the perceived remoteness of the ocean. The proposed activities will advance ocean related scientific teaching and education. The technology in development will help enliven the ocean in the classroom, moving from textbook knowledge to real-time interactions. The proposed activities will allow students to become more connected to the global environment. The technology will help educate the public in manner needed if society is to overcome the environmental problems humanity currently faces.
Carbon sedimentation (10 Pg C/year) via the ocean bio-carbon pump (Fig 1) is important to the regulation of atmospheric CO2. Due to limitations of current observational methodology (moorings/ships), carbon export (or sedimentation) is poorly observed in space and time and thus is poorly understood and parameterized in carbon cycle simulations. Technology capable of autonomous operation in the ocean will enable improved carbon-cycle prediction. This project addressed a major gap in upper ocean carbon flux observations through the substantial completion of the development of the Carbon Flux Explorer (CFE), a fully autonomous robotic system designed to measure (and relay in real time via Iridium satellite link) the hourly/diurnal variations of particulate organic carbon (POC) and particulate inorganic carbon (PIC) sedimentation at various depths in the upper kilometer(s) of the ocean for seasons to year-long time scales. CFEs are the successful integration of the Sounding Oceanographic Lagrangian Observer (SOLO) float (developed at Scripps) and LBNL/UC Berkeley’s imaging Optical Sediment Recorder (OSR).The SOLO dives to its target depth and the optical sedimentation recorder (OSR) begins operation. During time at depth sinking particles settle into a high aspect ratio funnel before reaching the sample stage. The particles are imaged under Dark Field, Transmitted, and Transmitted – cross-polarized illumination. The OSR executes a hydrodynamic cleaning cycle and collects a reference image set, and sleeps. At timed intervals the OSR wakes up and repeats image sets. Cleaning occurs after a set number of image sets. After the specified number of hours at depth, the OSR takes another image set, does stage cleaning, and takes a final reference image set. The SOLO surfaces to report position, engineering data, CTD data, and OSR data; it then dives to its next planned depth. At project start in October 1 2009, we began with a 14 point list of CFE development needs which included: (1) addressing the failure of the CFE to sink on its first deployment in 2007 due to adsorbed air, (2) A tilt of 5° while under water, and (3) a pressure induced optical interference with cross polarized light imaging. The project assessed (4) bio-fouling of the sample imaging stage, (5) fouling by gelatinous organisms and tentacles during up-profile, (6) and migrator invasion. The project further (7) simplified the CFE complexity by using a symmetric layout (Fig 2) and elements of the SOLO pressure case design; (8) replaced the PTP protocol Nikon camera (Bishop, 2009) with a faster low power Sumix imager; (9) remade the down light (Fig. 2) and below-sample polarizer with higher transmissivity polarizers to enable shorter image exposure times; (10) modified the firmware controlling polarizer rotation to allow only a single crossed and uncrossed position to minimize pixel offsets of images and thus simplify image processing; (11) used lower cost and more simplified Li battery packs; (12) replaced the limited Linux Arcom computer with a Linux Gumstix cpu; (13) migrated many OSR functions to a low-power microcontroller; and (14) completed engineering documentation for most assemblies to facilitate technology transfer. Utilizing 7 research vessel expeditions, the project was able to sytematically test and prove new system elements and achieve a robust CFE design capable of operation in high sea states. The project improved CFE mission capability from ~7 days to 8 months (at hourly resolution) and two CFEs completed open ocean missions lasting 41 days (2011 – California Current) and 10 days (2013 – subarctic N Pacific); bio-fouling of optics and instrument has been minor. Software algorithms for off-line data reduction have been developed. Multiple expeditions from 2011 through 2013 to the 1900 m deep the Santa Cruz Basin, CA have yielded scientific dividends. An unprecidented CFE image data set (Fig 3) has enabled the comparison of satellite remotely sensed phytoplankton blooms and carbon sedimentation beneath such blooms. The project further quantified the substantial differences between sedimentation rates from the BUOY-OSR which is dangled below surface buoys vs. those from the CFE operating at the same depth, time and place. This project and OCE 0964888, provided laboratory, and seagoing experience for UC Berkeley undergraduates. In the last 4 years, 25 individual UC Berkeley undergraduates have participated in 11 (7 this project) expeditions, some as sole participants: (15F; 10M - including 4 Hispanic Americans (1F/3M); 4 Asian Americans (2F/2M); and 2 with disabilities (1F/1M); most have not yet graduated. Eight (2F/6M) have advanced to graduate schools in oceanography, chemistry, environmental law, and engineering. In Feb. 2013, the project began working with the San Francisco Exploratorium to improve public outreach in the area of the science of the ocean’s carbon cycle. The effort has been both ways: Berkeley is developing demonstrations on the 'hidden' carbon in sea water. The Exploratorium has just sponsored a telepresence session for the PI's freshman class "Oceans" which featured 30 minutes of live interaction with scienntists aboard Bob Ballard's ship, the Nautilus.
