Among the more important bathymetric features of the northern 

 Greenland Sea are the extension of the Mid-Oceanic Ridge with its 

 associated rift-valley which lies slightly to the west of Svalbard 

 and the Greenland, Hovgaard , and Spitsbergen fracture zones (Fig. 2). 



For many years, it generally was considered that a relatively 

 shallow sill (the Nansen Sill) with a maximum depth of approximately 

 1500 meters extended from northern Svalbard to Greenland and separated 

 the deeper waters of the Greenland Sea from the Polar Basin (Nansen 

 1902, 1915, Sverdrup 1933, Sverdrup, Johnson and Fleming 1942). However, 

 more recent hydrographic surveys indicate that such a sill probably 

 does not exist. The shoalest barrier between the Greenland Sea and 

 the adjacent Arctic Ocean now appears to be the Hovgaard Fracture 

 Zone which lies to the south of the proposed region of the Nansen 

 Sill. Lationov, Shamontev, and Yanes (1960) feel that the maximum 

 depths of this barrier are on the order of 3000 meters, and Johnson 

 and Eckhoff (1966) believe that the maximum sill depth is not less 

 than 2600 meters. The deepest saddle in this sill appears to lie 

 between the western extremities of the Hovgaard Fracture Zone and 

 the Greenland Continental Slope. 



2. Some Climatic Factors. 



According to the Air Weather Service (1946) , mean monthly surface 

 air temperatures in the survey area range from approximately -20°C 

 in February to 2°C in August, and the annual precipitation in the 

 region is approximately 250 mm/year. Zaitsev, Fedosov, Iljina, and 

 Ermachenko (1961) claim that the annual evaporation in this region 

 is also about 250 mm/year. 



Winds at Danmarks Havn (76°46'N, 18 C 46'W), which is slightly 

 to- the southwest of the survey area, and at Nord (81°40'N, 17°50'W), 

 which is somewhat to the northwest of the survey region, are usually 

 less than 15 knots (Det Danske Meteorologiske Institut 1961) . Severe 

 sea and swell conditions do not frequent the survey region (U.S. Navy 

 Hydrographic Office 1958). 



3. The Ice Regime. 



Surface currents create a distinctive ice distribution in the 

 survey region. In the western sector, the East Greenland Current 

 carries approximately 2000 km 3 of ice out of the Arctic Ocean every 

 year (Timofeev 1958, Lationov et al. 1960, Mosby 1962), and as a 

 consequence, this region usually has a heavy ice cover (Fig. 3). 

 Except for the more northerly portions of the survey area and the 

 portions which are close to Svalbard, the eastern sector is usually 

 ice-free because of the influence of the warm north setting West 

 Spitsbergen Current. 



Ice which is carried out of the Arctic Ocean by the East Greenland 

 Current is usually several years old and hummocked. Its average 



