Certified b VERTICAL MOTION IN THE ATLANTIC CIRCULATION PATTERN

requirements for the degree of Master of Science. A simple model of oceanic circulation is established on the basis of the distribution of radiocarbon in the Atlantic Ocean. This radioactive isotope, formed in the upper atmosphere by cosmic rays and introduced into the surface ocean by way of the carbon dioxide exchange, decays with a half life of 5570 years. The differences in radiocarbon concentration then should be related to the mixing rates. In view of the low temperature of the deep waters it is apparent that downward diffusion of heat from the warm surface layers must be balanced by a slow upward transport of water from depth. The radiocarbon model is established with the aim of studying these motions. The values of vertical transport obtained are found to be comparable to horizontal exchanges and therefore very important in the Atlantic circulation pattern. Average vertical velocities of the order of one centimeter per day are found, thus substantiating estimates made by Robinson and Stommel from a consideration of theoretical thermocline models