PETTBRSSON— INTRODUCTORY 



VI 



Atlantic Water 



Arctic water 



Continental 

 coast-water 



The distribution of the Atlantic water, according to the depth, is shown by 

 the two hydrographical sections on page V, of which Fig. 3 represents a section 

 across the Norwegian Sea between lyofoten and Jan Mayen '^, and Fig. 4 a section 

 across the North Sea^ along the 60''' degree of Latitude for January 1903. The 

 Atlantic water is denoted by shading. 



From the chart as from the sections, we see that water-layers of different origin, 

 designated by strokes and points, also occur in addition to the Atlantic water. 

 Thus, on the left (western) side of the Atlantic water-area in the chart, and on the 

 left side and underneath in the section Fig. 3 (Norwegian Sea) there is Arctic 

 water (shown by strokes); and on the right (eastern) side of the Atlantic area on 

 the chart and Fig. 4 (North Sea section) as far, for example, as the coast of the 

 Scandinavian Peninsula, there is so-called coast- or bank-water (shown by points). 



The sections Fig. 3 and Fig. 4, which are on the' same scale of lengths and 

 depths, give a representation of the distribution of the Atlantic water in the deep 

 Norwegian Sea and in the relatively shallow North Sea. The quantity of that 

 water is greater indeed in the Norwegian Sea than in the North Sea, but in the 

 former sea it seems to play but a secondary role in comparison with the surrounding 

 water-masses. The principal mass of water in this region consists, namely, of cold 

 water of Arctic origin, which forms both the surface layer between Greenland and 

 the Atlantic area, and the deeper layers, 2 — 5cxx)m deep, of the Norwegian Sea. 



In the Norwegian Sea, therefore, we find Arctic water both on the surface 

 and in the depths. Both arise, in part, from the Polar Stream: partly, from the ice- 

 bearing Greenland Polar Stream and the East Icelandic Polar Stream ordinarily 

 ice-free, and partly from the Icelandic coastal stream which forms a branch of the 

 latter; in part, from a mixture of the waters of the Polar Stream and Atlantic 

 Stream. Opinions still differ regarding the origin of the Arctic bottom-water^. 

 The peculiar characteristic of this water, which fills the large troughs of the deep 

 region of the Norwegian Sea from the bottom to the level of the submarine ridge 

 between Scotland and Iceland, aboixt 400—600 m below the surface, is its low tem- 

 perature, which goes down to — 1.3° C. and is the lowest to be found in the deep 

 regions of any of the oceans on the Earth 1 



On the eastern side of the Atlantic Stream and in the Barents Sea, in the 

 Norwegian Channel and in the Skager Rak, we find a mixed water which is 

 formed of Atlantic water and coastal water from the fjords of the mainland and 

 the so-called Baltic Stream coming from the Skager Rak. 



Arctic plankton-forms are sometimes found in this eastern boundary-water of 

 the Norwegian Sea and North Sea, especially in spring. This has led to the sup- 



1 Constructed from F. Nansen's preliminary account of the first cruise of the "Michael Sars" in 

 August 1900. 



2 According to the German investigations during the fishery cruise in January 1903 with the 

 steamer "Poseidon". Mitteil. d. deutschen Seefischerei- Vereins. October 1903. 



3 See F. Nansen, "The Oceanography of the North Polar Basin"; Norwegian Polar Expedition, 

 Nr. 9, p. 146; and O. Pettersson, "On the Influence of the Ice-melting upon Oceanic Circulation"; 

 The Geographical Journal. September 1904. XXIV. Nr. 3, p. 319. 



4 With a single exception, namely, in Bransfield Sound in the Antarctic regions, where O. 

 Nordenskiöld has recently found a temperature of — i-6°C. at a considerable depth. 



