normal barometric pressure distribution in February has a gra- 

 dient approximately normal to the trend of the Labrador-New- 

 foundland coast with pressures decreasing offshore, and practically 

 no gradient in a direction parallel to the coast, so that normally the 

 February winds contribute to the Labrador Current and southeast- 

 erly movement of the ice. Figure 14 illustrates the extent of the 

 departure from normal of the barometric pressure distribution 

 during February 1947. The interval between lines of equal anomaly 

 of barometric pressure is two millibars. 



The onshore component of the winds in the Labrador-Newfound- 

 land area during February, and to a smaller degree in March, 

 resulted in the destruction of a major part of the ice crop which 

 would otherwise have reached the Grand Banks region during the 

 1947 season. This is an aspect of the effect of barometric pressure 

 distribution which is not taken into account in the Smith iceberg 

 forecast formulae. The magnitude of the gradient producing such 

 an effect is given in the foregoing table. The circumstances existing 

 in 1947 are provocative of speculative inquiry. One question which 

 arises is whether a strong offshore component of the wind, if sus- 

 tained for several weeks, would not also result in the destruction of 

 a year's berg crop since the water of the Labrador Sea northeast- 

 ward of the continental slope is markedly warmer than is the water 

 on the shelf. In answer, only a surmise is possible at the present 

 time. The sea ice probably would be destroyed as effectively whether 

 the component were directed onshore or offshore. However, the 

 bergs driven aground by onshore winds are temporarily immobi- 

 lized while their destruction proceeds. The immobilization not only 

 impedes their southward travel but subjects them to greater me- 

 chanical stresses from heavy seas and therefore is likely to increase 

 the rate at which they calve growlers and glacial debris. Because of 

 the surface over which the onshore winds passed before arriving in 

 the vicinity of the ice, higher probable air-temperatures lead to the 

 expectation that the melting of the ice exposed to the air will pro- 

 ceed more rapidly than when the winds are offshore. One should 

 expect that any onshore or offshore components in the winds will 

 result in a reduction of the number of bergs reaching the Grand 

 Banks region, and that the onshore winds will be more effective than 

 offshore winds in bringing about such a reduction. 



■j;^^ U. S. GOVERNMENT PRINTING OFFICE: 1949—827714 



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