scribed below; three of the ten 

 buoys deployed were Horizon 

 Marine minibuoys; two were 

 MET Ocean minibuoys 

 (CMOD). The International 

 Ice Patrol deployed the 

 minibuoys to compare the in- 

 formation received from them 

 and their characteristics with 

 that of the larger, more expen- 

 sive buoys the Ice Patrol has 

 used traditionally. The five 

 minibuoys were used for re- 

 search purposes only. They 

 were tested to determine their 

 long-term survivability. Infor- 

 mation gained from this study 

 will be published by the Inter- 

 national Ice Patrol in an ap- 

 propriate fonjm at a later date. 



The standard 

 configuration for the opera- 

 tional buoys was a 3-m-long 

 spar hull with a 1 -m-diameter 

 flotation collar. Each buoy 

 was equipped with a 2-m by 

 10-m window shade drogue 

 attached to the buoy with a 

 50-m tether of 1 .3-cm (0.5 in) 

 nylon. The center for the 

 drogue was at a nominal 

 depth of 58 m. Each buoy had 

 a temperature sensor (accu- 

 rate to approximately 1°C) 

 mounted approximately 1 m 

 below the waterline, a drogue 

 tension monitor, and a battery 

 voltage monitor. Two of the 

 buoys deployed during 1990 

 (9877 and 9878) were 



Page 50 



equipped with barometric 

 pressure sensors funded by 

 the U. S. Navy. 



The data from 

 the buoys are acquired and 

 processed by Service 

 ARGOS. Ice Patrol queries 

 the ARGOS data files and 

 stores the buoy data once 

 daily. Most of the buoy posi- 

 tion data fall within the stan- 

 dard accuracy provided by 

 Service ARGOS (approxi- 

 mately 350 m). Operational 

 buoy data were entered 

 into the Global Telecommuni- 

 cations System (GTS) using 

 their assigned World 

 Meteorological Organization 

 (WMO) numbers. 



BUOY DEPLOYMENT 

 STRATEGY 



Monitoring the 

 currents with drifting buoys 

 in the entire Ice Patrol 

 operations area (40°N to 

 52°N; 39°W to 57°W) for the 

 entire iceberg season is im- 

 practical. A recent study 

 (FENCO 1987) showed that 

 at least 400 buoys would be 

 required to resolve the eddy 

 field in a 250-km by 250-km 

 area, an area less than 5% of 

 MP's total operational area. 

 The costs associated with 

 deploying and tracking hun- 

 dreds of buoys far exceeds 



the entire Ice Patrol budget. 



Per our general 

 approach, Ice Patrol's 1990 

 buoy deployment strategy fo- 

 cused on the current that is 

 the major conduit of icebergs 

 to the North Atlantic shipping 

 lanes, the southward flowing 

 off-shore branch of the Labra- 

 dorCurrent. Generally IIP at- 

 tempts to monitor this current 

 forthe entire season by keep- 

 ing one or two buoys in it at all 

 times. 



Buoys are de- 

 ployed as far north as pos- 

 sible within the OPAREA 

 (north of 50°N) because the 

 southward mean flow of the 

 Labrador Current carries the 

 buoys into the southern areas 

 of interest. Ice Patrol's expe- 

 rience has shown that this 

 approach is reasonable within 

 limitations. Early in the ice- 

 berg season (March and April), 

 buoys can not be deployed in 

 areas with significant concen- 

 trations of sea ice (<3/1 0) be- 

 cause wind-driven movement 

 of the sea ice contaminates 

 the drifter data, and sea ice 

 can damage the buoy. In many 

 cases buoys deployed be- 

 tween 50°N to 52°N move 

 eastward north of the Flemish 

 Cap, and therefore do not en- 

 ter our primary region of inter- 

 est south of Flemish Pass. It 

 is frequently necessary to 



