The mean pressure pattern for July 1973 (figure 281.) was 

 as close to its normal as meteorlogically possible. The 

 Bermuda-Azores High was 4 mb. higher than normal but the 

 isobars were almost perpendicular to the Labrador coast 

 indicating southwesterly winds and no further southerly 

 iceberg drift wind component. Winds were from the west-south- 

 west over the Grand Banks providing little southward movement 

 to the remaining icebergs and enabling Ice Patrol to close 

 out the season by the end of the month. The pressure chart 

 for August as shown in figure 28j . is included for continuity. 

 The pressure pattern was near normal, but with the Icelandic 

 Low of 1005 mb . and a 1017 mb . high centered over Greenland, the 

 isobars are much closer providing for a much greater than 

 normal southerly flow along the Labrador coast. The previous 

 months warmer temperatures took their toll on the iceberg 

 population, however, in that only one additional iceberg 

 drifted south of 48°N. 



Northwesterly winds have a profound effect on icebergs and 

 their drift. These winds create a southerly component of wind 

 induced iceberg drift, accentuate the volume transport (and 

 velocity) of the Labrador Current, reduce the air and sea 

 surface temperatures, and spreads and develops sea ice to the 

 south and east of Newfoundland. To determine and assign 

 numerical values to the existing wind conditions, surface 

 pressure gradients (differences in atmospheric pressure along 

 a geographically orientated line) may be used. Six such 

 gradients are labeled in figure 29. Gradients 1 and 2 measure 

 the winds off the coast of Labrador which are important in 

 setting up the drift for transporting icebergs to the general 

 area northeast of Newfoundland. Gradient 3 measures the 

 component which assists or impedes icebergs as they drift 

 along the eastern slope of the Grand Banks. Gradient 4 is 

 a measure of the influence of the generally westerly winds 

 along the northern slopes of the Grand Banks. This is 

 important in drifting the icebergs away from the northeast 

 Newfoundland coast and into the Labrador Current. If, however, 

 they are too strong (or persistent) when the bergs reach the 

 northeast corner of the Grand Banks, they may be carried 

 eastward out of the Labrador Current and into warmer waters 

 which drift generally northeastward. Gradients 5 and 6 

 provide a pre-season indication of potential iceberg drift 

 south and across Davis Strait, respectively. 



-18- 



