departures were evident, especially over Baffin 

 Bay and along the coast of Labrador (negative 

 anomolies of 11 mb and 13 mb, respectively). 



April brought a return to near-normal patterns 

 and pressures with the Icelandic Low at 1003 mb 

 only 4 mb below normal and located at its normal 

 position southwest of Kap Farvel. The Azores 

 High at 1025 mb was only 4 mb higher than 

 usual and about 5° west of its normal location. 

 Thus the winds were more northerly over the 

 Labrador coast and about the usual magnitudes. 



The May mean pressure pattern was more in- 

 tensive than normal with the difference between 

 the Icelandic Low and the Azores High more 

 than usual. They were both in their usual posi- 

 tions providing for the same wind directions but 

 larger magnitudes than normal. 



In June, for the first time this year, the differ- 

 ences between the Icelandic Low and Azores 

 High were less than normal. The June Icelandic 

 Low was at its normal pressure but was relocated 

 near 55°N 43°W rather than over the Labrador 

 coast and had a second center over Iceland. The 

 Azores High was in its usual position near 33°N 

 38 C W and about 2 mb lower than normal. The 

 departures from normal were thus small and con- 

 fined to a positive 4 mb anomoly off the Labrador 

 coast 



The July Bermuda-Azores High closely resem- 

 bled its usual features with the pressure pattern 

 off the Labrador and Newfoundland coasts being 

 mirror-images of the normal. In August the 

 mean pressure pattern intensified with the Ber- 

 muda-Azores High 2 mb higher than normal and 

 the 1005-mb Icelandic Low over 5 mb lower than 

 normal. The High over the Greenland Ice Cap 

 was 5 mb higher than normal at 1018 mb. The 

 resulting greater than norma 1 northwesterly 

 winds had little effect on the rapidly closing Ice 

 Season. 



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 defined in figure 27. 

 From an analysis of these gradients, inferences 

 can be made as to the northwesterly winds pro- 

 ducing southerly iceberg drift, accentuating the 

 Labrador Current, reducing the air and sea tem- 

 peratures, and spreading and developing sea ice 

 along the coasts of Labrador and Newfoundland. 



Gradients 1 and 2 measure the winds of the 

 coast of Labrador which are important in setting 

 up the drift for transporting icebergs to the gen- 

 eral area northeast of Newfoundland. Gradient 

 3 measures the wind component which assists or 

 impedes icebergs as they drift along the eastern 

 slope of the Grand Banks. Gradient 4 is a meas- 

 ure of the influence of westerly (or easterly) 

 winds along the northern slope of the Grand 

 Banks. This latter gradient is important in de- 

 termining iceberg drift away from the New- 

 foundland coast and into the core of the Labrador 

 Current. If the winds are too strong (or persist- 

 ent) when the bergs reach the northeast corner 

 of the Grand Banks, they may be carried out over 

 Flemish Cap and into the warm waters of the 

 North Atlantic Current. Gradients 5 and 6 pro- 

 vide a preseason indication of potential iceberg 

 drift south and west in the Davis Strait, respec- 

 tively. 



The 1974 pressure gradient statistics are shown 

 graphically in figure 27 in comparison with their 

 1946 — 1973 averages. Gradients 1 and 2 provide 

 a tremendous impetus to southerly iceberg drift 

 in January with almost three times the normal 

 values, then after mid- February they display a 

 continued above average value for the remainder 

 of the season. Icebergs didn't reach the area of 

 pressure gradients 3 and 4 until early March. 

 From then until mid-June Gradient 3 averaged 

 slightly negative while Gradient 4 slowly dimin- 

 ished from over three times its normal value to 

 slightly above normal. These gradients clearly 

 show very little, if any, southerly iceberg drift 

 potential once the iceberg reached the northern 

 Grand Banks region, and explain why that, in 

 spite of the excessive number of bergs, a surface 

 patrol was not required. The predominent west- 

 erly winds shown in gradient 4 kept most of the 

 icebergs out of the influence of the main Labra- 

 dor current drifting east over the Flemish Cap 

 area and limiting only a few bergs to the region 

 of the Tail of the Banks in June, relatively late 

 in the season when the waters are showing major 

 warming trends. Gradients 5 and 6 show large 

 deviations form normal in the critical January 

 through March time frame in the Davis Strait 

 area. Thus extra impetus was provided to ice- 

 bergs moving south through the Strait as well as 

 westward across it. 



11 



