Taro Takahashi and David W. Chipman; Lamont-Doherty Earth Observatory

"Measurements of CO₂ During the Southern Ocean JGOFS Program"

Water masses such as AABW and AAIW which originated in the high latitude Southern Ocean areas spread through the interior of the major ocean basins thus forming a major conduit for exchanges of heat and dissolved gases such as CO₂ and oxygen between the atmosphere and the interior of the oceans. Therefore, an improved understanding of the processes governing the physical, and biogeochemical properties of the sources waters in the Southern Ocean is important not only for gaining quantitative knowledge of the carbon-nutrient cycle in the global oceans, but also for predicting the future course of atmospheric CO₂ and hence the climate of the earth.

Our proposed program consists of the following field observations: 1) Continuous underway measurements of the p CO₂ and total CO₂ concentration in surface waters will be made throughout the JGOFS cruises aboard the R/V Thompson and R/V Palmer in order to determine the seasonal and geographic variations and the causes of oceanic CO₂ sink/source conditions; 2) Measurements of p CO₂ and total CO₂ in discrete seawater samples will be conducted to observe depth profiles of the CO₂ chemistry (especially in the upper 500 meters) at hydrographic stations located at various latitudes during two seasonal cruises aboard the R/V Thompson (the Spring Survey Cruise in October, 1997 and the Summer Survey Cruise in January, 1998); and 3) In order to document the mesoscale variability of biogeochemical properties in the upper 250 meters within the Antarctic Polar Front Zone, high resolution measurements of CTD/CO₂/nutrients will be conducted using a pumping SeaSoar system during either the Summer Survey Cruise in January, 1998, or the Autumn Process Study Cruise in March, 1988. The pumping SeaSoar system is presently being assembled at Lamont-Doherty Earth Observatory.