Distribution of radiocarbon in the western North Pacific: Preliminary results from MR97-02 cruise in 1997

In the transition area between the subarctic and subtropical regions in the western North Pacific, vertical distributions of radiocarbon at seven stations were clarified by AMS radiocarbon measurement in 1997. The radiocarbon in intermediate water at those stations indicate (1) direct ventilation of upper intermediate water above 26.6 sigma (theta) surface and (2) no temporal increment of radiocarbon in the transition area during the last two decades. These results positively suggest that the North Pacific intermediate water is formed in the transition area in the western North Pacific. (C) 2000 Elsevier Science B.V. All rights reserved.