Contributions of the Siberian shelf polynyas to the Arctic Ocean intermediate and deep water

Abstract

The role of the open water regions or polynyas in the winter ice pack over the Siberian continental shelves in the production of Arctic Ocean Intermediate and Deep Water is examined through use of a combination of passive microwave satellite data, coastal weather station data, and oceanographic data. The satellite data allow us to derive a time series of the open water areas of selected polynyas for the 1978–1982 winters. The polynyas which occur north of Svalbard, around Franz Josef Land, along the west coast and north end of Novaya Zemlya, and to the east of Severnaya Zemlya and the Taymyr Peninsula are the primary oceanographic contributors. The open water time series for these polynyas are used in combination with coastal weather station data to estimate the heat loss from each polynya. For the region north of Svalbard, which is historically known as Whalers Bay, the study shows that the heat loss is sufficient to provide the observed cooling of the West Spitsbergen Current. For the other polynyas the heat loss is used to compute the ice production rates and the oceanic salt flux. We then use the historic oceanographic salinities with the salt fluxes to estimate the contribution of each polynya to the Arctic Ocean water masses. If we assume that the salt contributes only to the Arctic Intermediate Water, our results show that the shelves are capable of producing about 20–60% of this water. Alternatively, if the salt contributes only to the deep water of the Eurasian Basin, then without consideration of the mixing of the bottom water with the Greenland and Norwegian Sea water, the contribution from the shelves yields a renewal time of about 100 years. Our results imply that there is insufficient water produced in the shelf polynyas to perform all of the roles that have been historically assigned to it.