Polynya activity in the Arctic Ocean from 1958 to 1997

Abstract

Arctic polynyas are investigated during 39 winter seasons from 1958 to 1997 by means of a polynya model forced by the National Centers for Environmental Prediction reanalysis data set of wind and air temperature. The model is able to reproduce polynya events (i.e., opening date, closing date, and size) at various locations around the Arctic Ocean. A mean ice production and corresponding salt flux from all Arctic polynyas of 300±30 km3 yr−1 and 6±0.6×l012 kg yr−1, respectively, is found. These values are ∼40% of the results in earlier satellite‐based investigations. The total annual ice production from polynyas shows a large interannual variability with a range between minimum and maximum values of 40% and with a distinct periodicy of 5 years. Single polynya events are shown to be important for the total ice production, with productions up to 5 m per event or some 50% of the seasonal mean in some areas. The mean salt flux from all polynyas can at maximum maintain a flow of 0.2 Sv with a salinity of 32.85 out from the shelves. This represents ∼30% of the estimated flux necessary to maintain the cold halocline layer of the Arctic Ocean. Areas contributing most to halocline water formation are the Barents, Kara, Chukchi, and Bering Seas, where the Chukchi Sea is the only area contributing actively to deep water formation. This investigation indicates that the cold and salty shelf waters formed in polynyas give a relatively small contribution to the intermediate and deep waters of the Arctic Ocean compared to other possible processes such as the modification of Atlantic water by cooling and ice melt.