OCEAN STATION VESSELS OF THE NORTH ATLANTIC 



The deep, open expanse of the ocean generally affords maxiraum uninter- 

 rupted fetch distances for wave development during migratoiy storms, the 

 wave heights being limited only by the duration of wind action. The major 

 storm track along the east coast of the United States continues northward 

 and northeastward toward Greenland and Iceland, where storms for a short 

 period often stagnate before moving on again, A blocking situation in the 

 upper air circulation may be such that a storm will stall at one location 

 perhaps for days at a time. During stagnation, the storms often retain 

 or increase their intensity of circulation. Since the ocean station ves- 

 sels mentioned here are in close proximity to major and secondary storm 

 tracks, the circumstances outlined above induce persistence of unfavorable 

 waves of longer durations at ocean station locations than at locations 

 near sheltering influences. 



The progression of storais through this region affects the northern 

 tier of ocean station vessels (north of 50*N. latitude) during all seasons. 

 Examination of the persistence curves in Figures 5A through 5l reveals, 

 as should be expected, that long durations of unfavorable waves of all 

 height categories are experienced by the northern tier of ocean station 

 vessels throughout the year. 



On the other hand, the southern tier of ocean station vessels (south 

 of 50*N, latitude) experiences long durations of unfavorable waves In autumn 

 and winter only, whereas favorable wave conditions persist for long periods 

 during the spring and summer. The reason is that the stonn tracks are well 

 to the north of the southern tier of ocean station vessels during the spring 

 and summer seasons, when the dominant climatic control is the Azores high 

 pressure system. 



31 



