deploy buoys directly in Flem- 

 ish pass to ensure that the 

 buoys will move to the south 

 because Ice Patrol requires 

 drift data in this area. To ac- 

 complish this objective buoys 

 often are deployed at 47°N 

 between 46-30°W and 47- 

 30°W. 



AIRCRAFT 

 DEPLOYMENTS 



Ice Patrol has 

 deployed satellite-tracked 

 buoys from HC-130 aircraft 

 since 1979. The buoy is 

 strapped into an air-deploy- 

 ment package and launched 

 out the rear door of an HC-1 30 

 flying at an altitude of 150 m 

 (500 ft) at 77 m/s (150 kts). 

 The air-deployment package 

 consists of a wooden pallet 

 and a parachute, both of which 

 separate from the buoy after it 

 enters the water. The para- 

 chute riser is cut by a cable 

 cutter that is activated by a 

 battery energized when im- 

 mersed in salt water. The 

 pallet separates when salt 

 tablets dissolve and release 

 straps holding the buoy to the 

 pallet. The buoy floats free, 

 and the drogue falls and un- 

 furls. The Ice Patrol air-de- 

 ployed 4 of these buoys 

 during the 1990 season. 

 The remaining 6 buoys were 

 ship- deployed. 



DATA PROCESSING 



The raw position 

 and temperature data are 

 relatively noise free, however, 

 all records are reviewed be- 

 fore processing to ensure qual- 

 ity control. Duplicate posi- 

 tions and positions with time 

 separations of 30 minutes or 

 less are deleted. Positions 

 less than 700 m from adjacent 

 positions are deleted, unless 

 the deletion results in a time 

 separation of four or more 

 hours. 



The quality-con- 

 trolled position data are then 

 fitted to a cubic spline curve to 

 arrive at an evenly spaced 

 record with time intervals of 

 three hours. This process re- 

 sults in a slight reduction in 

 the number of fixes per day 

 (from 10 to 8). The position 

 records are then filtered using 

 a low-pass cosine filter with a 

 cut-off of 1.6 X 10-5 Hz (one 

 cycle per day). This filter re- 

 moves most tidal and inertial 

 effects. The buoy drift speeds 

 are calculated at three-hour 

 intervals using a two-point 

 backward differencing 

 scheme. 



The trajectory 

 plots presented in this report 

 are from the filtered records. 

 Also presented for each buoy 



is a plot of the time history of 

 the U (eastward is positive) 

 and V (northward is positive) 

 components of velocity from 

 the filtered records. A time 

 history of the raw sea surface 

 temperature data is plotted for 

 each buoy. The dates used in 

 all of the plots are year-days, 

 which are numbered sequen- 

 tially starting at 1 on 1 Janu- 

 ary. The year-days are in- 

 cluded parenthetically in the 

 text. 



BUOY TRAJECTORIES 



The following 

 sections discuss each buoy 

 trajectory in chronological or- 

 der by buoy deployment date. 

 The discussions summarize 

 each buoy's performance and 

 the data it contributed to Ice 

 Patrol operations. The sum- 

 maries are not intended to be 

 an exhaustive data analysis. 

 Buoy data from the area east 

 of 39°W, the eastern bound- 

 ary of the Ice Patrol's opera- 

 tions area, are not presented. 

 Data from the IIP buoy pro- 

 gram are archived at the IIP 

 office in Groton, Connecticut 

 and the Marine Environmen- 

 tal Data Service (MEDS), De- 

 partment of Fisheries and 

 Oceans. 



Page 51 



