92 



The floating stations are comparable in many respects to the more iso- 

 lated shore stations. They are subject, however, to transportation over con- 

 siderable distances in the Arctic, uncontrolled and more or less unpredictable, 

 and in this respect are connparable to a ship frozen in the ice. The problems 

 to be undertaken would be of similar nature and much of the instrumentation 

 would be the same. Consider Nansen's FRAM expedition (Nansen, 1897) and 

 Papanin's drift on the ice floe (Papanin, 1939) allowing for the advances in 

 science over the intervening years. The ice floe may provide more freedom 

 in the geographic position of initiating investigations in the pack but this can 

 hardly offset the advantages of comfortable living quarters and well equipped 

 scientific laboratory of the ship. The floating station must be established and 

 supplied by plane and later removed, barring natural catastrophe, by plane or, 

 if late in the life of the ice floe, by ship. Considerable permanency may be ex- 

 pected, although not positively assured, on the so-called ice islands (Fletcher, 

 1951) (Koenig and others, 195Z) as T-3 (Fletcher Island). The numbers of these 

 are limited. Of themselves they afford many unique problems. 



Supporting Electronic Gear Used in Navigation and Ice Detection - The electron- 

 ic gear useful for detecting the presence of ice at sea are radar and sonar (un- 

 derwater sound ranging). These devices were greatly improved during the war 

 years for target location without, however, any alterations for the explicit pur- 

 poses of studying the ice. The detection of ice by radar is essentially the same 

 problem as that of any other floating target. Although the echo from an iceberg 

 is weaker than that from a steel ship of comparable above water size. In cases 

 of unusual channeling near the sea surface, icebergs have been detected at dis- 

 tances approaching 100 miles but the normal range is miore frequently 10 to 50 

 per cent of this distance. Sea ice is detected at ranges up to ten or more miles. 

 In rough seas, isolated cakes or small bergs may be obscurred by sea clutter 

 on the radar scope and missed entirely. Within the ice limits seas are normal- 

 ly smooth and radar shows the open leads. Beyond a few miles reliability de- 

 creases rapidly with distance. It is anticipated that devices used to minimize 

 sea clutter will be as effective on ice as they will be on other types of targets. 



The problem of target identification by radar, distinguishing ice from 

 other targets, is still with us. Indirect methods using relative motion are 

 useful, but there is little difference in quality of echo from a drifting dory or an 

 ice cake. 



Sonar perhaps suffers more in picking up ice than other targets. This is 

 in part due to the irregular water structure with marked gradients in tempera- 

 ture and salinity that frequently occur near pack ice peripheries. Ice targets 

 may be missed entirely by this device. Mechanical improvements in sonar, 

 enabling it to better detect submerged or floating targets, will be effective on 

 ice where the water conditions favor suitable transmission. 



Next to detecting the ice itself, the defining of its geographic position is 

 perhaps most important. Ice areas are notoriously bad for determining posi- 

 tion by astronomical navigation. In high latitudes, when weather is not overcast 

 or stormy or foggy, refraction may be quite serious. In the Grand Bank area, it 

 is possible to cruise days on end without suitable astronomical fixes. 



The installing of loran stations during the war years greatly assisted the 

 navigator in determining his position. Using loran and radar, it was possible 

 to scout the boundaries of ice fields and off-lying bergs from ship or plane. 

 Improvements in the accuracy in loran for ship and plane navigation will to the 

 same extent increase the accuracy of defining the position of ice encountered. 



Shoran is another device used for precise positioning over line-of-sight 



