Surface Water in the Eurasian Basin of the Arctic Ocean

Abstract

T HE Arctic Ocean can be separated, on the basis of temperature and salinity characteristics of the water, into a three-layered system. This layered nature of the water in the Arctic Ocean was first observed by Nansen (1902) who, ,during the drift of the Fram, noted that the top layer of the sea, between 0 and 200 metres consisted of water of low salinity and low temperature ; this layer was termed by him "genuine polar water". From 250 m. to the bottom the sea was filled with water of very high salinity and relatively high temperature, which evidently originated in the Atlantic Ocean and was slightly modified on the way to the Arctic Ocean. The temperature of the deeper water was above 0°C. down to about 900 m. and less than 0°C. below 900 m. but not so cold as the upper polar water. Studies have been conducted since the expedition on the Fram with ever increasing intensity. These studies have not altered the basic concept of the physical oceanography of the Arctic Ocean as elucidated by Nansen, but they have added much detail. The considerable amounts of station data that have been accumulated over many years, and during all seasons of the year, show a remarkable regularity of the distribution of temperature and salinity at depth throughout the year, as well as repeating seasonal regularities in the surface waters. [It should be noted that in waters as cold as those in the Arctic Ocean the vertical distribution of density so closely parallels that of salinity that the latter may be used as an index of the mass distribution ,] This close approach to a steady state in the observed distribution of these properties is apparently the result of continuing processes within the basin. Because of this the layered waters of the Arctic Ocean can be divided into water masses with defined characteristics of temperature and salinity, and analyses can be made of their origin and distribution without recourse to synoptic data. The Lomonosov Ridge divides the Arctic Ocean into two major d e e p water basins, the Canadian and the Eurasian, as shown in Fig. l a (LaFond