The air-deployment package failed 

 inhalf (3of 6)ofthe1988 

 launches. The failures were 

 similar in that the wooden pallet 

 that holds the buoy and drogue 

 together broke apart when it 

 entered the HC-130's airstream. 

 In all cases the parachute oper- 

 ated properly and the buoys 

 descended to the surface at a 

 normal speed. Two of the buoys 

 (4563 and 4566) transmitted 

 normally, but one (4564) failed to 

 transmit after its deployment. It is 

 not certain that the buoy failure 

 was due solely to the failure of the 

 drop package. In most cases the 

 buoy survives and the most 

 serious result is that the parachute 

 remains attached to the buoy hull. 

 When this happens the parachute 

 can act as a near-surface drogue 

 until it collapses and entangles 

 with the buoy hull or drogue tether. 



DATA PROCESSING 



Although the raw position and 

 temperature data are relatively 

 noise free, all records are scanned 

 before processing to ensure 

 quality control. First, duplicate 

 positions and positions with time 

 separations of 30 minutes or less 

 are deleted. Then, positions < 

 700 m from adjacent positions are 

 deleted, unless the deletion results 

 in a time separation of four or 

 more hours. 



The error-free position data are 

 then fitted to a cubic spline curve 

 to arrive at an evenly-spaced 

 record with an interval of three 

 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 removes 

 most tidal and inertial effects. 

 Finally, the buoy drift speeds are 

 calculated at three-hour intervals 

 using a two-point backward differ- 

 encing scheme. 



f^ost of the trajectory plots pre- 

 sented 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) compo- 

 nents of velocity from the filtered 

 records. Finally, 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-dates, which are numbered 

 sequentially starting at 1 on 

 January 1 . In the text, the year- 

 dates are included parenthetically. 



BUOY TRAJECTORIES 



In the following sections each 

 buoy trajectory is discussed 

 separately, presented in chrono- 

 logical order by buoy deployment 

 date. Only the operational buoys 

 are discussed. 



The intent of the following discus- 

 sions is to summarize each buoy's 

 performance and the data that it 

 contributed to Ice Patrol opera- 

 tions. It is not intended to be an 

 exhaustive data analysis. The 

 buoy data from the area east of 

 39°W, the eastern boundary of the 

 Ice Patrol operations area, are not 

 presented. All of the data from the 

 IIP drifting buoy program are 

 archived at the IIP office in Groton, 

 Connecticut. 



63 



