Investigation of the atmospheric and surface ocean pCO/sub 2/ in the Indian Ocean. Final technical report

The results of measurements for the concentration of CO/sub 2/ in the marine air and the partial pressure of CO/sub 2/ (pCO/sub 2/) in the surface ocean water obtained during the Geosecs Expedition in the north and south Indian Oceans, December 1977 through April 1978 are summarized. The area studied covers 13/sup 0/N to 64/sup 0/S in latitudes and 55/sup 0/E to 115/sup 0/E in longitudes. It has been found that the atmospheric CO/sub 2/ concentration in the southern hemisphere south of 15/sup 0/S is remarkably constant at 334 +- ppM (expressed as mole fraction of CO/sub 2/ in dry air) throughout the period of this investigation. The CO/sub 2/ concentration in the northern hemisphere from the equator to 13/sup 0/N exceeds that in the southern hemisphere by up to 5 ppM. The Inter-Tropical Convergence Zone (ITCZ) appears to represent a transition zone for the atmosphere CO/sub 2/ distribution. The surface water pCO/sub 2/ values in the Indian Ocean range from 300 microatm. to 360 microatm. The highest values were observed in the Arabian Sea, and appear to be due to the low alkalinity water flowing out of the Red Sea. The Indian equatorial water has a maximum pCO/sub 2/ value of about 335 microatm., which is about 10 microatm. (or 3%) greater than that in the atmosphere. The Indian Ocean data were combined with those previously obtained in the Pacific and Atlantic Oceans to yield a global mean pCO/sub 2/ value for the surface ocean water. It is found that the global mean pCO/sub 2/ for the world oceans is 10 +- 8 microatm. lower than the mean atmospheric pCO/sub 2/ value. This indicates that the net transfer rate of CO/sub 2/ from the atmosphere to the oceans corresponds to 50 (+-40)% of the industrial CO/sub 2/ production rate