that early in the iceberg season 

 (March and April), buoys are not 

 deployed in areas with significant 

 concentrations of sea ice ( > 3/1 0) 

 because wind-driven movement of 

 the sea ice contaminates the drifter 

 data, and sea ice can damage the 

 buoy. In many cases buoys de- 

 ployed between 50°N to 52°N move 

 eastward to the north of Flemish 

 Cap, and hence do not enter the 

 region south of Flemish Pass. Be- 

 cause Ice Patrol requires drift data 

 in this area, it is frequently neces- 

 sary to deploy buoys directly in the 

 Pass to ensure that the buoy will 

 move to the south. In this case the 

 buoys are deployed at 47N between 

 46-30W and 47-30W. 



Despite concerns over deployment 

 in sea ice mentioned above, during 

 the early part of the 1989 season 

 buoy deployment was pushed to the 

 north to support LIMEX '89 (see 

 Appendix C). 



AIRCRAFT DEPLOYMENTS 



Ice Patrol has deployed satellite- 

 tracked buoys from HC-130's since 

 1979. The buoy is strapped into an 

 air-deployment package and 

 launched out the reardoor of an HC- 

 1 30 flying at an altitude of 500 ft ( 1 50 

 m) at 150 kts (77 m/s). 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 ener- 

 gized when immersed in salt water. 

 The pallet separates when salt tab- 

 lets dissolve and release straps 

 holding the buoy to the pallet. The 

 buoy then floats free and the drogue 

 falls free and unfurts. 



Page 64 



The manufacturer redesigned the 

 air deployment package for use in 

 the 1 989 season following a 50 per- 

 cent failure rate in 1988. None of 

 the re-designed air deployment 

 packages failed during 1989. 



DATA PROCESSING 



Although the raw position and tem- 

 perature data are relatively noise 

 free, all records are reviewed before 

 processing to ensure quality control. 

 First, duplicate positions and posi- 

 tions with time separations of less 

 than 30 minutes are deleted. Then, 

 positions less than 700 m from adja- 

 cent positions are deleted, unless 

 the deletion results in a time separa- 

 tion of 4 or more hours. 



The quality-controlled position data 

 are then fitted to a cubic spline curve 

 to arrive at an evenly spaced record 

 with time intervals of 3 hours. This 

 process results in a slight reduction 

 in the number of fixes per day (from 

 10 to 8). Next, the position records 

 are filtered using a low-pass cosine 

 filter with a cut-off of 1 . 1 6 x 1 0-5 Hz 

 (one cycle per day). This filter re- 

 moves most tidal and inertial effects. 

 Finally, 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 (east 

 is positive) and V (north is positive) 

 components of velocity from the fil- 

 tered records. Finally, a time history 

 of the raw sea surtace temperature 

 data is plotted for each buoy. The 

 dates used in all of the plots are 

 year-days, which are numbered se- 

 quentially starting at 1 on January 1 . 

 In the text, the year-days are in- 

 cluded parenthetically. 



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 

 that it contributed to Ice Patrol op- 

 erations. It is not intended to be an 

 exhaustive data analysis. The buoy 

 data outside of the Ice Patrol op- 

 erations area, east of 39 W and north 

 of 52N, are not presented. The data 

 from the IIP buoy program are 

 archived at the IIP office in Groton, 

 Connecticut and the Marine Envi- 

 ronmental Data Service (MEDS), 

 Department of Fisheries and 

 Oceans, Halifax, N.S.. 



Buoy 9875 



Buoy 9875 was deployed at 1937Z 

 on 25 March (84) at 48-30N, 48- 

 OOW. It remained within the Ice 

 Patrol operations area for 62 days, 

 passing north of 52°N on 26 May 

 (146) (Figure B-la). The drogue 

 sensor indicatedthatthe drogue was 

 connected until 15 October (288). 

 The buoy stopped transmitting on 

 23 December (357). 



From deployment until day 96 the 

 buoy drifted eastward north of the 

 1000-m contour at roughly 20 cnvs 

 (Figure B-lb). Between days 96 

 and 1 34 the motion of the buoy was 

 complex. Speeds varied from 2 to 

 25 cm/s, and the temperature ranged 

 from 3°C to 7°C. On day 134 the 

 buoy began a northward drift with 

 speeds increasing up to 100 cm/s 

 and temperature increasing from 

 4.5°C to 9°C. 



Buoy 9876 



Buoy 9876 was deployed at 2027Z 

 on 25 March (84) at 48-OON, 48- 

 59W. It failed on 30 March (89) 



