Ventilation in the Arctic Ocean and the Role of Pacific Inflow Deduced From Transient Tracer Measurements

Abstract

AbstractDuring the seventh Chinese National Arctic Research Expedition, measurements of CFC‐12 and SF6 were used to estimate ventilation time scales and anthropogenic CO2 (Cant) concentrations in the Arctic Ocean and Bering Sea based on the transit time distribution (TTD) method. The profile distribution showed that there was a high CFC tongue entering through the Canada Basin in the intermediate layer (27.6 kg m−3 < σθ < 28 kg m−3), at latitudes between 75 and 85°N, related to the inflow of Atlantic water. The result shows that both intermediate and deep/bottom waters are better ventilated in the Arctic Ocean than in the Bering Sea. The mean age gradient of the Bering Sea Surface Water and Pacific water core of the southwest Canada Basin (24.7 < σθ < 26.2) could be a consequence of intensive mixing and entrainment of the inflow water from the Bering Sea. An expected difference in age between these areas was interpreted to reflect the transit time for the given water layers. Thus, a mean transit time from the Bering Sea (175.2–179.9°E, 59.7–61.6°N) to the western Arctic Ocean (151.6–158°W, 73.1–74.8°N) of 14.6 ± 4.6 years was estimated. The mean Cant column inventory in the upper 2,000 m was higher (~45 mol m−2) in the Arctic Ocean than in the Bering Sea (~25 mol m−2).