STRENGTHS AND LIMITATIONS OF PROPOSED RESEARCH 



The carbon cycle on continental margins is difficult to describe from measurements 

 because many of the contributing processes vary rapidly in time and space. Furthermore, the 

 carbon pools that make up the carbon cycle, DIC, POC and DOC, and their rates of change can 

 be measured only from ships. The new capability to make moored measurements of dissolved 

 oxygen allows time series observations of the change in 2 to be used as a surrogate for changes 

 in C0 2 . Moored measurements of dissolved 2 can capture episodic events in the carbon cycle. 

 Oxygen is an integrating variable and the measurements from the moored array can hopefully be 

 extrapolated to a larger region. 



Oxygen is not a perfect surrogate for CO z . Oxygen exchanges much more rapidly with 

 the atmosphere than does C0 2 and the relative exchange rates vary with conditions. The air-sea 

 exchange of C0 2 is best estimated from direct measurements of the difference in partial pressure 

 of C0 2 across the air-sea interface, delta pC0 2 , and physical state of the marine boundary layer. 

 Oxygen budgets for the upper mixed layer must include air-sea exchange of 2 , which can be 

 estimated from measurements of 2 and total gas tension. 



STATUS OF RESEARCH 



Our success at making moored measurements of dissolved oxygen in the SEEP II 

 experiment created considerable scientific interest because such measurements can be used to 

 verify air-sea gas flux models and to create oxygen budgets for the mixed layer. In phase one 

 of OMP, we participated in several field experiments to test instruments and demonstrate that 

 moored measurements of 2 can be used to study the carbon cycle. 



In February 1993, two BNL moored fluorometers, a solar irradiance sensor, and four YSI 

 oxygen monitoring systems were deployed offshore of La Perouse Bank in the North Pacific 

 Ocean (48.5 °N and 127 °W). This heavily instrumented, moored array also included: gas 

 tension devices, acoustic current meters, neutrally buoyant mixed layer floats, several sonar 

 systems, thermistor chains, and surface following platforms. The experiment was designed to 

 measure (1) near-surface circulation, (2) air- sea gas flux and breaking wave dynamics, (3) ocean 

 surface acoustical reverberation, and (4) the near-surface oxygen budget. Results from this 

 experiment are being used to develop measurement strategies for OMP field experiments. 



High resolution TOYO data collected in May 1993 aboard the RV Gyre have been used 

 to design a moored array capable of resolving diel changes in 2 to a specified error. The 

 temperature, fluorescence, salinity, oxygen and photosynthetic parameter fields were analyzed 

 using krigging techniques to derive objective error estimates for proposed mooring designs. 



In March 1994, an array of four moorings containing one FRR photosynthesis, eight 

 oxygen, and seven fluorescence sensors was deployed near Cape Hatteras to test our ability to 



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