A Model for the Thickness and Salinity of the Upper Layer in the Arctic Ocean and the Relationship between the Ice Thickness and Some External Parameters

Abstract

This paper presents a dynamical model for the salinity and thickness of the upper layer in the Arctic. The parameters are the river runoff to the Arctic, the buoyancy supply through the Bering Strait, the export of ice from the Arctic and a parameter characterizing the vertical mixing. An ice model is formulated, having the following two important properties: 1) the horizontal surface area of the exported ice is essentially determined by external parameters (the wind field over the Arctic); and 2) there is a relationship between the ice thickness and the fraction of open water in the Arctic. The model for the upper layer and the ice model are used together with a heat budget for the Arctic, also including the effect of different albedo for ice and open water. A relationship between the freshwater supply and the ice thickness is derived. Also investigated are the effects on the ice thickness of a changed export of ice area and changed properties of the flow through the Bering Strait. It is found that a decrease of the fresh-water supply by as much as 50% would have only a small effect upon the ice thickness and the fraction of open water in the present Arctic Ocean. However, if such a decrease of the freshwater supply is combined with a moderate decrease of the flow through the Bering Strait and with a likewise moderate increase of the area of the exported ice, the pack ice might disappear.