year (not necessarily the same year) in order to resolve the anticipated large seasonality in the 

 oceanic C0 2 sink/source condition. Early spring (pre-bloom) and late spring (post-bloom) 

 measurements will allow the magnitude of the effect of the spring bloom to be determined, while 

 summer, fall and early winter measurements will allow the rate of recovery from the 

 bloom-induced drawdown of C0 2 to be determined. We do not at present have sufficient 

 seasonal data to evaluate the temporal variability of the surface seawater pC0 2 , but anticipate that 

 it will be greatest at the time of the spring phytoplankton bloom and will vary more slowly 

 during the remainder of the year. 



Based on our preliminary measurements in the Cape Hatteras region and the shelf /slope 

 area between Hatteras and Georges Bank, the surface seawater pC0 2 spatial variability is greatest 

 in the near-shore environment, especially in the vicinity of estuaries, while the offshore areas 

 show relatively low- frequency variability except in the waters affected by the Gulf Stream. 



METHODS AND PLATFORMS 



Quasi-continuous measurements of surface seawater C0 2 partial pressures will be made 

 from one or more of the ships carrying out the hydrographic measurements in the OMP field 

 area, as well as possibly from other ships operating within the area, with the exact number and 

 timing of cruises selected to maximize the temporal and spatial coverage. Our IR-based system 

 has been successfully operated during one cruise by essentially untrained technicians from 

 another institution (BNL) without undue burden, demonstrating that personnel limitations need 

 not limit the cruises in which we may participate. We presently operate several of these systems 

 on assorted ships-of-opportunity, and anticipate having at least one system available to devote 

 totally to this project. 



In the event that the development of buoy-mounted pC0 2 sensors is successful, it will be 

 vital to have comparison measurements made several times during the year, so that the close 

 temporal spacing of the measurements made at these few fixed locations can be tied to the broad 

 spatial coverage of the shipboard system. This may require the operation of a second IR system 

 on the buoy-tending vessel. 



STRENGTHS AND LIMITATIONS OF PROPOSED RESEARCH 



The greatest strength of our approach is that it is based on a proven analytical technique 

 (we have had a comparable system operating continuously on Lamont's vessel , the R/V Ewing, 

 for more than two years); the new generation of solid-state IR analyzers has been shown to be 

 highly reliable in the difficult shipboard working conditions. 



The principal limitation of the approach is the restriction of data acquisition to periods 

 when a suitably instrumented ship is operating within the survey area. Proxy measurements made 



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