Environmental Conditions, 

 1989 Season 



The wind direction along the La- 

 brador and Newfoundland coasts 

 can affect the iceberg severity of 

 each ice year since the mean wind 

 flow can influence iceberg drift. 

 Dependent upon wind intensity 

 and duration, icebergs can be ac- 

 celerated along or driven out of 

 the main flow of the Labrador 

 Current. Departure from the La- 

 brador Current normally slows 

 their southerly drift and, in many 

 cases, speeds up their rate of 

 deterioration. 



The wind direction and air tem- 

 perature indirectly affect the ice- 

 berg severity of each ice year by 

 influencing the extent of sea ice. 

 Sea ice protects the icebergs from 

 wave action, the major agent of 

 iceberg deterioration. If the air 

 temperature and wind direction 

 are favorable for the sea ice to 

 extend to the south and over the 

 Grand Banks of Newfoundland, 

 the icebergs will be protected 

 longer as they drift south. When 

 the sea ice retreats in the spring, 

 large numbers of icebergs will be 

 left behind on the Grand Banks. 

 Also, if the time of sea ice retreat 

 is delayed by below normal air 

 temperatures, the icebergs will be 

 protected longer, and a longerthan 

 normal ice season can be ex- 

 pected. The opposite is tnje if the 

 southerly sea ice extent is minimal, 

 or if above normal airtemperatures 

 cause an early retreat of sea ice 

 from the Grand Banks. 



The following discussion summa- 

 rizes the environmental conditions 

 along the Labrador and New- 

 foundland coasts for the 1989 ice 

 year. 



January: The monthly mean 

 pressure of the Icelandic Low was 

 about 18 mb lower in January 



than normal (Figure 2). The winds 

 for the month were from the 

 northwest over the Labrador Coast 

 (AES, 1989). 



February: The mean Icelandic Low 

 forthe month was northeast of Iceland 

 and lower than normal. The Azores- 

 Bermuda High was 10 mb higher 

 than normal (Figure 3). As a result, 

 tfie mean winds over Newfoundland 

 arxj Labrador during the nronth were 

 colder and more westerly than normal 

 (AES, 1989). 



March: The ninthly mean pressure 

 for the month shows a summer-time 

 Azores-Bermuda High and a winter- 

 time Icelandic Low (Figure 4), and 

 thus both were nnore intense than 

 normal (Mariner's Weather Log, 

 1989a). This resulted in 20 mb 

 negative anomalies over Iceland and 

 lOmb positive anomalies in thie mid 

 North Atlantic. The prevailing wirxJs 

 continued to be nnore westerly than 

 normal along the Labrador and east 

 Newfoundland coasts (AES, 1989). 



April: The Azores-Bermuda High 

 covered a large part of the North 

 Atlantic and was 5 rrb higher than 

 normal (Figure 5). As expected, the 

 Icelandic Low spread out from La- 

 brador to Iceland, but, unexpectedly, 

 it also covered Europe, creating 

 negative anomalies (Mariner's 

 Weather Log, 1989b). Moderate 

 northwest to westerly winds prevailed 

 over east Newfoundbndwaters(AES, 

 1 989) ratherthan the normal northerly 

 winds. 



May: The Azores-Bermuda High 

 had an extension covering from Nova 

 Scotia to eastern Europe (Fixjre 6). 

 This extension covered the area usu- 

 ally occupied by the Icelandic Low, 

 resulting in a band of positive 

 anomalies (Mariner's Weather Log, 

 1989b). The mean windflow was 



from the southwest fortfie first part of 

 the month and then shifted to north- 

 westerly (AES, 1989). Light 

 southwesterlies usually prevail 

 throughout the month. 



June: Although ttieAzores-Bennuda 

 High was weaker than normal, it still 

 covered nrost of tfie North Atlantic 

 (Figure 7). The Icelandic Low was 

 over Greenland, north of its normal 

 position, resulting in a slightly higher 

 than normal pressure off Labrador. 

 Winds were very light over the regbn 

 during the montfi. 



July: The Azores-Bermuda High 

 covered most of the North Atlantic, 

 and it also extended over the United 

 Kingdom, thus creating positive 

 anomalies in this region (Figure 8). 

 Although a weak high normally exists 

 over Greenland, a mild Icelandic Low 

 persisted in this area during July 

 (Mariner's Weather Log, 1990). The 

 winds were typical southwesteriies. 



August: The Icelandic Low was 

 centeredover Iceland and much nrx>re 

 intense thian normal, aeating up to 

 10-mb negative aromalies (Figure 

 9). The mean pressures for the re- 

 gion were abnormal due to the in- 

 tense bw and a midsummer Azores- 

 Bermuda High (Mariner's Weather 

 Log, 1990). 



September: The Icelandic Low 

 usually reappears during Septenv 

 ber, but this year it was already 

 present in August (Mariner's Weather 

 Log, 1990). The Icelandic Low was 

 nxire extensive than normal, ttxxigh, 

 and thus aeated negative anomalies 

 (Figure 10). The Azores-Bermuda 

 High was approximately normal, but 

 slightly nnore intense than normal 

 around the edges. There was a 

 normal westerly flow over New- 

 foundland. 



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