reports were made and radiosonde observations were made daily 

 at 1600 G. c. t. In addition the experimental vessel made and 

 transmitted 3-hourly synoptic surface weather observations when- 

 ever it was at sea and more than 200 land miles from the nearest 

 weather observing ship or shore station. The experimental vessel 

 occasionally took radiosonde observations at unscheduled times in 

 connection with the radar experimental work. On days when no 

 such observations were made the radiosondes were taken at the 

 scheduled times. A digest of weather conditions experienced is 

 given in the cruise summaries. 



COMMUNICATIONS 



As has always been true, radio communication continues to be 

 among the most important factors in International Ice Patrol in 

 both the collection and dissemination of ice information. This 

 international service is conducted for the benefit of shipping and 

 cannot be successful without the fullest cooperation of all vessels 

 plying the North Atlantic. This cooperation has been given whole- 

 heartedly, and in acknowledging such indispensable assistance a 

 request is made for its extension to include suggestions and criti- 

 cisms which may point the way toward an improved service. 



It may be noted that certain changes have been made with the 

 resumption this year of the International Ice Patrol after a period 

 of four war years. The A-1 and A-2 emission broadcasts, intended 

 to reach ships with different types of equipment, were formerly 

 transmitted at different times. In 1946 they were keyed simultane- 

 ously and the times of the scheduled twice-daily broadcasts were 

 adjusted to permit the inclusion of a maximum of recently re- 

 ceived information. The morning broadcast comes at a time cal- 

 culated to include the digested reports which increase in number 

 during the first few hours after dawn with its improved visibility. 

 The time of the evening broadcast is intended to permit the inclu- 

 sion of the results of aerial ice observation flights which usually 

 return to the base field shortly before dusk. The A-2 emission 

 was formerly on a frequency of 425 kilocycles, which is a busy 

 commercial frequency. In order to relieve congestion on this fre- 

 quency, the A-2 emission is now broadcast on 480 kilocycles. 



The following daily schedule of ice broadcasts to shipping was 

 maintained from 1 March until 28 July. Each broadcast was pre- 

 ceded by a general call on 500 kilocycles after which the transmit- 

 ting station (Radio Argentia, NWP) announced the NIDK ice 

 bulletin with the operating signal to shift to 480 and 8100 kilo- 

 cycles. After shifting to these frequencies there followed a 30- 

 second period of test signals to permit receiver tuning. The ice 

 bulletin M'as then broadcast twice, the first transmission being 



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