SUMMARY OF ICE PATROL, SEASON OF 1923. 



Bv Commander B. M. Chiswell, Senior Officer. 



The patrol was inaugurated by the Seneca, which arrived off the 

 Tail of the Grand Bank March 13, when she was reHeved by the 

 Tampa. Thereafter the Tampa and Modoc alternated on ice patrol 

 duty every 15 days until the discontinuance of the patrol on July 12. 



The month of March was characterized by unusually stormy 

 weather, the wind reaching gale force on 3 of the 6 days of the Seneca's 

 patrol and 1 1 of the 13 of the Tampa's. All gales were from SW. to 

 NW, Only about 9 per cent of fog and reduced visibility was ex- 

 perienced for this period. Water temperatures showed that the 

 Labrador Current had assumed an unusual drift to the SE. between 

 Flemish Cap and the east slope of the Grand Banks. This was 

 further shown by the drift of numerous bergs as far east as the steamer 

 tracks to northern European ports, between lats. -14° 20' and 46° 00', 

 which led the patrol to spend more time than usual east of the Grand 

 Banks in the vicinit}' of the steamer tracks mentioned. The breaking 

 up and disintegration of bergs was remarkably rapid and was caused 

 by the high sea-water temperatures and the buffeting they received 

 from the tempestuous seas. In one instance a large berg wholly 

 disintegrated in three days, which is most unusual. Only three bergs 

 drifted around the Tail of the Bank during the month, and these but 

 little south of the 43d parallel. Field ice was reported as far south as 

 42° 20', which is somewhat farther south than it is usually seen. The 

 trans-Atlantic steamer tracks were shifted 60 miles to the southward, 

 effective March 30 for eastbound vessels and April 6 for those west- 

 bound. 



During the month of April fog and low visibihty prevailed approxi- 

 mately 51 per cent of the time, and three gales were encountered. 

 The tendenc}' of the bergs to drift off to the eastward before reaching 

 the Tail of th.e Bank, observed in March, continued during the first 

 half of April, one being reported on April 13 as far east as 39° 42' 

 W. and 43° 05' X. By the middle of the month, however, this easterly 

 drift had ceased and subsequent drift was to the southward along the 

 east side of the Banks, then to the westward around the Tail of the 

 Bank, and finally to the NW.. many of them grounding along the 

 SW. slope of the Bank. Xo steamer lanes were threatened during 

 the month and the southernmost berg observed was in 42° 40' X., 



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