SUMMARY REPORT OF COMMANDER INTERNA- 

 TIONAL ICE PATROL 



The ice patrol was inaugurated March 22, when the Tampa sailed 

 from Boston. The Modoc left Boston in sufficient time to relieve the 

 Tampa after she had been on duty for 15 days. These two Coast 

 Guard cutters then alternated on duty throughout the remainder of 

 the season, one of the vessels being continuously on guard in the ice 

 regions. This work required a total of seven cruises, and Halifax, 

 Nova Scotia, was made the port of call at which fuel and supplies 

 were obtained. The patrol service was discontinued on June 25 

 when a dispatch from headquarters directed the vessels to return to 

 their respective stations. The total period during which the vessels 

 were on guard was 95 days — 3 days short of the time in 1926. 



The patrol work has been for some few years regarded as having 

 two general features: First, and of primary importance, is the actual 

 search carried on by the patrol; the collecting of all the ice reports 

 from passing vessels; and the dissemination of this information four 

 times daily. Second only to the foregoing is the scientific work 

 which in late years has centered on frequent surveys of the currents 

 which transport the ice about to various menacing positions. 



We wish in referring to the practicable work this year to briefly 

 summarize the general distribution of ice and its behavior. A dis- 

 cussion of the subject is carried in greater detail under the section 

 devoted to ice observation (p. 52), to which the reader's attention is 

 invited. As early as March 11, a prediction was made in accordance 

 with an iceberg forecasting equation (see Bull. No. 15, p. 48) that 

 396 bergs would drift south of Newfoundland for the season of 1927. 

 It developed actually that there was slightly more ice during the 

 spring of 1927 than occurs in a normal year about 380, and this 

 agreement between fact and prediction lends added confidence to 

 such a method of iceberg forecasting for future years. Although the 

 number of bergs south of Newfoundland (below the forty-eighth 

 parallel), was slightly above the average, the amount of ice around 

 the Tail of the Bank and near the United States-Europe steamship 

 tracks was remarkably deficient. The interference in the normal 

 distribution is attributed to two factors, (1) the predominance of 

 northeasterly winds during the early part of the season and, (2) the 

 unusual inshore invasion of warm counter oceanic currents. The 

 discussion of these features in considerable detail will be found under 



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