retreated about 200 miles along the east slope of the Grand Banks and 

 the temperature at the Tail has risen 4° F., from 44° to 48° F. 



It is noted that an airborne radiation thermometer was tested by the 

 International Ice Patrol during the past ice season. "Wliile the actual 

 water temperatures recorded by this instrument were not considered 

 sufficiently reliable, the instrument was useful in detecting changes 

 in surface water temperature, and therefore in locating the Labrador 

 Current and its branches. The most successful use of this instrument 

 was obtained during an Ice Patrol flight on 22 May. See figure 16. 

 In order to obtain acceptable sea surface temperatures with this 

 instrument, correction factors for moisture content in the air and for 

 sea-air temperature differences must be determined. It must also be 

 understood that the microsurf ace temperature is being determined and 

 this temperature may vary significantly from the water temperature 

 at a depth of a foot or more. It is expected that the airborne radiation 

 thermometer will eventually serve to abundantly increase our knowl- 

 edge of berg environment. 



The sea surface at the Grand Banks and vicinity is only a small por- 

 tion of the berg environment there. An isotherm chart including tem- 

 peratures below the sea surface or the average temperature to a given 

 depth would more completely depict the environment. However, sub- 

 surface data are obtainable only from the Ice Patrol Oceanographic 

 Vessel, which conducts oceanographic surveys in the area about half 

 the time during the ice season. This year the International Ice Patrol 

 Office constructed isotherm charts based on average temperatures from 

 the surface to 150 meters for each oceanographic survey from data 

 supplied by the oceanographic vessel. See figures 11-15. The centi- 

 grade scale was used, as this scale is becoming universal for recording 

 sea temperatures. There is nevertheless reluctance to convert the bi- 

 monthly surface isotherm charts to centigrade as the fahrenheit scale 

 has been used by the Ice Patrol for these charts since their first con- 

 struction over 40 years ago. It is hoped that average temperature 

 charts, which reflect below-surface temperatures, will be constructed 

 annually and eventually result in normal charts which will be more 

 useful than the normal charts based entirely on surface temperature. 

 In the meantime, the normal surface charts will be useful in determin- 

 ing whether the existing berg environment is normal or abnormal and 

 therefore in forecasting ice conditions. Surface sea temperatures gen- 

 erally reflect subsurface temperatures even in the region of the greatest 

 variety of oceanographic conditions in the world known as the Grand 

 Banks and vicinity. 



In order that the isotherm charts can become more useful in forecast- 

 ing, berg deterioration studies must be accomplished on a scientific 

 basis. Berg observation by Ice Patrol vessels has been abundant in 

 the past, but little scientific data on deterioration has accompanied the 



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