Fifth Ice Patrol Cruise, "Acushnet," 3 June to 10 June 1950 



Departing Ai-gentia the afternoon of 3 June, the Acushnet proceeded 

 to the vicinity of 46°00' N., 50°30' W., and reHeved the Tampa 

 of the duties of ice-patrol vessel on 4 June. The Acushnet then 

 headed for the Tail of the Grand Banks and was able to search the 

 vicinity of 42°45' N., 50°00' W., in good visibility. No recent ice 

 observations had been made on the eastern edge of the Grand Banks 

 northward from this position, so the Acushnet set a course to the 

 north and scouted both visually and by radar to 47°50' N., 48°50' W., 

 which position was reached about noon on the 8th. The course was 

 then changed to the southward to search the Grand Banks for bergs 

 especially the berg sighted by the Tampa on 4 June in 46°19' N., 

 48°30' W. Ice patrol aircraft searched the areas to the south in 

 good visibility on 8 June but sighted no ice east of 50° W., and south 

 of 46°40' N. A search of the area within 50 miles of the last reported 

 position of the berg sighted by the Tampa on 4 June was completed 

 on 9 June without sighting any ice. The surface vessel patrol was 

 discontinued at 1200 G. c. t. 10 June 1950 and the Acushnet headed 

 for Argentia arriving there the same date. The service of ice obser- 

 vation was continued until 26 June by aircraft. 



For this short patrol, fog was present 43 percent of the time which 

 is greater than the average of 30 percent shown on the Pilot Chart 

 of the North Atlantic Ocean for June 1950. Ho>vever, it was observed 

 that visibility in fog was better on this cruise than on previous cruises. 

 No gales or violent seas were experienced. Meteorological obser- 

 vations were restricted to six-hourly synoptic weather reports. 



Following is a summary of ice and water temperature reports 

 received on this cruise. 



Number of ice reports received 10 



Number of vessels furnishing ice reports 13 



Number of water temperature reports received 140 



Number of vessels furnishing water temperature reports 39 



Number of vessels furnished special information 22 



A discussion of the six ice observation flights made during this 

 cruise is contained in the description of ice conditions for June. 



DISCUSSION OF WIND EFFECTS 



Analysis of wind effects on ice movements in the Grand Banks area 

 was made in 1947 and 1949 using weather maps obtained from the 

 aerology office at Argentia. (See bulletins 33 and 35 of this series.) 

 This procedure was followed in a similar analysis for the 1950 season 

 but because of certain gaps in the data, recourse was finally made 

 to the monthly mean sea level charts published by the United iStates 

 Weather Bureau. 



Average pressure gradients were computed from the differences in 

 pressure along the sides of a rectangle 600 miles long by 180 miles wide 

 centered at 51°00' X., 51'00' W., for each month. These were com- 



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