Mid-1980s Distribution of Tritium, He-3, C-14 and Ar-39 in the Greenland Norwegian Seas and the Nansen Basin of the Arctic-Ocean

The distributions of tritium/He-3, C-14 and Ar-39 observed in the period between 1985 and 1987 in the Greenland/Norwegian Seas and the Nansen Basin of the Arctic Ocean are presented. The data are used to outline aspects of the large-scale circulation and the exchange of deep water between the Greenland/Norwegian Seas and the Nasen Basin. Additionally, semi-quantitative estimates of mean ages of the main water masses found in these regions are obtained. Apparent tritium/He-3 ages of the upper waters (depth <500m) vary from close to zero in the Norwegian Current to about 15 years at the lower boundary of the Arctic halocline. The deep waters (>1,500m depth) of the Greenland/Norwegian Seas show apparent tritium/He-3 ages between about 17 years in the Greenland Sea and 30 years in the Norwegian Sea. Ar-39 based estimates of the Nansen Basin intermediate, deep and bottom water ages are 91(-23)+26, 161(-44)+50 and 277(-31)+33 years for Arctic Intermediate Water (AIW), Eurasian Basin Deep Water (EBDW) and Eurasian Basin Bottom Water (EBBW), respectively. Within the errors, age estimates of EBDW and EBBW based on C-14/tritium correlations are consistent with those derived from Ar-39 (163 to 287 years for EBDW and 244 to 368 years for EBBW). A quantitative evaluation of the data in terms of deep water formation and exchange rates based on box model calculations is presented in an accompanying paper.