APPENDIX A 

 ICEBERG TAGGING AND TRACKING PROJECT 1974 



R. Q. ROBE 

 USCG Research and Development Center 



R. W. SCOBIE 



R. M. HAYES 



USCG Oceanographic Unit 



INTRODUCTION 



During the 1974 Ice Patrol Season the Coast 

 Guard Research and Development Center and the 

 Coast Guard Oceanographic Unit conducted an 

 iceberg drift project aboard the Coast Guard 

 Cutter EVERGREEN. This project provided 

 average drift vectors for six icebergs in the 

 Grand Banks of Newfoundland area over a 

 period of three to six days. The results were 

 forwarded to Commander, International Ice 

 Patrol (IIP). Comparisons could then be made 

 by IIP between the observed drift values and 

 those predicted by computer model. Icebergs 

 were tagged to allow for the surveillance of a 

 number of bergs distributed over an area of up 

 to 300 square miles. This also assured positive 

 identification upon subsequent visits to obtain 

 position fixes. In the past, attempts have been 

 made to mark icebergs using dye, however, ice- 

 berg melting, rain, wave action, and iceberg roll- 

 ing often caused the dye patches to be washed 

 away. The complications involved in tagging a 

 berg for future recognition center around the 

 dynamic nature of an iceberg. 



Icebergs near the Grand Banks normally melt 

 rapidly. A berg's rate of decay was a function of 

 its environment and internal structure. Deteriora- 

 tion was hastened by warm sea and air tempera- 

 tures, as well as by rough seas. Rivulets of 

 melting water were seen cascading down the sides 

 of some icebergs creating large channels on the 

 surface and often collecting in pools in the basin 

 areas. Others of the drydock variety had wave 

 cut embayments which concentrated wave forces 

 and speeded deterioration. Large chunks of ice 



often calved off icebergs to accelerate their de- 

 struction. Instabilities, which resulted from de- 

 terioration, caused icebergs to pitch and yaw and 

 in severe cases to roll over completely. In con- 

 sequence of these dynamic changes, it was very 

 difficult to put anything on, or attach any device 

 to, an iceberg that would remain in position long 

 enough to give positive identification over a sig- 

 nificant time interval (i.e., about 5-7 days). 



METHODS 



During the International Ice Patrol 1974 sea- 

 son a method was tested for the relocation and 

 differentiation of icebergs used in drift studies 

 near the Grand Bank region. The bergs were 

 surrounded by an array of floats (styrofoam 

 cylinders) connected by buoyant line (polypro- 

 pylene, 3/8" diameter). The length of this line 

 varied from 400 to 800m depending upon the size 

 of the iceberg. A spar-type, buoyant RDF trans- 

 mitter was included in the line circle. One hun- 

 dred and eighty degrees from the transmitter was 

 a spar buoy with a radar reflector for electronic 

 detection and/or red flags for visual detection 

 (Figure A-l). Each RDF transmitter had a 

 different transmission frequency to permit posi- 

 tive identification independent of visual observa- 

 tion. The transmitters were located with an 

 automatic direction finder mounted on the bridge. 

 The antenna for this system was secured to the 

 railing just forward of the bridge. Early at- 

 tempts at locating the RDF transmitters using 

 handheld receiving sets were frustrated by the 

 apparent omnidirectionality of the signal at 

 ranges closer than 3700m as well as directional 

 ambiguity at greater distances. 



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