Arctic Ocean water mass balance from isotope data

The distributions of the oxygen 18 and tritium isotopes, and of salinity, yield a residence time of 10 years for the surface and halocline waters of the Arctic Basin. We find a yearly net production of 0.59 m of sea ice and an input of 1.16 m of freshwater from continental river runoff, local precipitation, and Bering Strait salinity deficiency. Using the basin area value with these numbers gives long‐term average total net production and transport rates of 0.15 Sv of ice and 0.18 Sv of meteoric component, Bering Strait water not included. If, in addition, a reasonable depth profile of relative current velocity is assumed for the outflow, a yearly input of 2.8 Sv of Atlantic and Bering Strait water is needed to replenish the upper and halocline waters. These numbers should be good to ±20% and are multiyear averages. The isotope data clearly indicate that the Barents Sea is an inflow area for Atlantic water to the basin, but that net export of ice occurs there.