Appendix B 



TIROS Oceanographic Drifter Tracks on the Grand 

 Banks During the 1986 International Ice Patrol Season 



LT lain Anderson, USCG 



Introduction 



During the 1986 International Ice 

 Patrol season, nine TIROS 

 Oceanographic Drifting buoys 

 were deployed in the Ice Patrol 

 operating region. Three of the 

 nine drifters were used exclusively 

 for data gathering in conjunction 

 with the IIP-1-86 cruise and these 

 data are discussed in Appendix C. 

 Of the six buoys used operation- 

 ally, five were deployed by HC- 

 130 aircraft during regular ice re- 

 connaissance flights. The sixth 

 was deployed by USCGC EVER- 

 GREEN as part of IIP-1-86 cruise 

 and was not recovered so that its 

 track could be used operationally. 



An oceanographic cruise was 

 conducted using USCGC EVER- 

 GREEN (WMEC 295) from 22 

 April until 22 May 1986. The 

 primary objective of the cruise was 

 to provide surface truth data for an 

 airbome radar study of an oce- 

 anic front south of Flemish Cap. 

 The results of the cruise are 

 discussed in Appendix C. 



The International Ice Patrol uses 

 drifting buoys for real-time current 

 information for weekly updates to 

 the historical current field used in 

 its iceberg drift model (Summy 

 and Anderson, 1983 and Summy, 

 1982). Drifters are deployed for 

 operational use in areas of high 

 iceberg density and in areas of 

 high variability in the current field 

 to improve drift prediction. All of 

 the drifters except drifter 4547 

 were deployed to monitor the 

 variability of the Labrador Current. 

 Drifter 4547 was deployed near 



the end of the Ice Patrol season in 

 the area of the highest remaining 

 iceberg concentration. 



All of the buoys deployed by Ice 

 Patrol are three meters long and 

 have a spar-shaped hull with a 

 flotation collar. They are equipped 

 with a sea surface temperature 

 sensor, a drogue tension sensor, 

 and a battery voltage monitor. 

 The temperature sensor is located 

 approximately one meter below 

 the surface. Each drifter is 

 deployed with a 2m by 10m 

 window shade drogue attached to 

 the drifter by a 50m tether. An 

 average of nine positions per day 

 was received from each opera- 

 tional drifter with position accuracy 

 of approximately 300m (Bessis, 

 1981) The positions and sensor 

 data points are evenly distributed 

 in time except for the period 

 between OOZ and 04Z when 

 virtually no data are received. 

 This null data period is due to the 

 orbits of the NOAA series satel- 

 lites. 



As of 30 September 1986, no 

 drifter remained transmitting in the 

 Ice Patrol region (Table B-1). Two 

 drifters (4542 and 4547) were 

 recovered intentionally by Coast 

 Guard cutters. Drifter 4557 was 

 picked up by an unknown vessel. 

 Drifter 4552 stopped transmitting 

 28 days after deployment. The 

 remaining two drifters (4543 and 

 4549) are still drifting across the 

 North Atlantic, providing data 

 outside the Ice Patrol region. 



All air-launched buoys deployed 

 properly except 4552. Its para- 

 chute opened but the wooden 

 frame holding the buoy broke 

 apart in the air. Because of this 

 the parachute did not cut free from 

 the buoy after splashdown. The 

 remainder of the air-dropped 

 drifters deployed properly and the 

 parachutes released from the 

 drifter packages. 



The following section describes 

 the data from the satellite-tracked 

 buoys used by Ice Patrol during 

 the 1986 iceberg season. It is not 

 intended as an exhaustive data 

 analysis. The data are archived at 

 the International Ice Patrol, Avery 

 Point, Groton, CT 06340. 



Buoy Trajectories 



The tracks of the operational 

 buoys are discussed below in 

 chronological order based on the 

 deployment date. The numbers in 

 parenthesis following dates are 

 year dates (numbered sequentially 

 from 1 January through 31 De- 

 cember). 



4543 



Buoy 4543 was deployed on 26 

 March 1986 (85) from an HC-130 

 aircraft in the Flemish Pass at 

 46°59.3'N 47°19.6'W (Figure B- 

 1a). After deployment, it moved 

 southwesterfy, following the 

 bathymetry, with an average 

 speed of 61 cm/s until it encoun- 

 tered an oceanic front on 30 

 March (89). (This front was the 

 focus of IIP-1-86 cruise and is dis- 



45 



